Add LSPS1 client-side integration

[tnull]

We add the capability to act as an LSPS1 / bLIP-51 client.

[tnull]

Rebased on main after #426 landed.

[tnull]

Rebased on main to resolve minor changes.

[tnull]

Now went ahead and squashed fixups, including the doc changes:

> git diff-tree -U2 0e590ba9 b1a277c6
diff --git a/src/liquidity.rs b/src/liquidity.rs
index 7414260c..cbc19954 100644
--- a/src/liquidity.rs
+++ b/src/liquidity.rs
@@ -224,9 +224,9 @@ where
                                                match sender.send(response) {
                                                        Ok(()) => (),
-                                                       Err(e) => {
+                                                       Err(_) => {
                                                                log_error!(
                                                                        self.logger,
-                                                                       "Failed to handle response from liquidity service: {:?}",
-                                                                       e
+                                                                       "Failed to handle response for request {:?} from liquidity service",
+                                                                       request_id
                                                                );
                                                        },
@@ -285,9 +285,9 @@ where
                                                match sender.send(response) {
                                                        Ok(()) => (),
-                                                       Err(e) => {
+                                                       Err(_) => {
                                                                log_error!(
                                                                        self.logger,
-                                                                       "Failed to handle response from liquidity service: {:?}",
-                                                                       e
+                                                                       "Failed to handle response for request {:?} from liquidity service",
+                                                                       request_id
                                                                );
                                                        },
@@ -343,9 +343,9 @@ where
                                                match sender.send(response) {
                                                        Ok(()) => (),
-                                                       Err(e) => {
+                                                       Err(_) => {
                                                                log_error!(
                                                                        self.logger,
-                                                                       "Failed to handle response from liquidity service: {:?}",
-                                                                       e
+                                                                       "Failed to handle response for request {:?} from liquidity service",
+                                                                       request_id
                                                                );
                                                        },
@@ -390,9 +390,9 @@ where
                                                match sender.send(response) {
                                                        Ok(()) => (),
-                                                       Err(e) => {
+                                                       Err(_) => {
                                                                log_error!(
                                                                        self.logger,
-                                                                       "Failed to handle response from liquidity service: {:?}",
-                                                                       e
+                                                                       "Failed to handle response for request {:?} from liquidity service",
+                                                                       request_id
                                                                );
                                                        },
@@ -442,9 +442,9 @@ where
                                                match sender.send(response) {
                                                        Ok(()) => (),
-                                                       Err(e) => {
+                                                       Err(_) => {
                                                                log_error!(
                                                                        self.logger,
-                                                                       "Failed to handle response from liquidity service: {:?}",
-                                                                       e
+                                                                       "Failed to handle response for request {:?} from liquidity service",
+                                                                       request_id
                                                                );
                                                        },
@@ -964,6 +964,11 @@ pub(crate) struct LSPS2BuyResponse {
 /// Should be retrieved by calling [`Node::lsps1_liquidity`].
 ///
+/// To open [bLIP-52 / LSPS2] JIT channels, please refer to
+/// [`Bolt11Payment::receive_via_jit_channel`].
+///
 /// [bLIP-51 / LSPS1]: https://github.com/lightning/blips/blob/master/blip-0051.md
+/// [bLIP-52 / LSPS2]: https://github.com/lightning/blips/blob/master/blip-0052.md
 /// [`Node::lsps1_liquidity`]: crate::Node::lsps1_liquidity
+/// [`Bolt11Payment::receive_via_jit_channel`]: crate::payment::Bolt11Payment::receive_via_jit_channel
 #[derive(Clone)]
 pub struct LSPS1Liquidity {