refactor: Refactor of the publish path and HttpTransport (#162)

To improve the testability of publishing a package,
`PyOci.publish_package()` is split into multiple methods.

Tests for the refactored parts were moved/restructured so it is no longer needed
to go through the entire request flow for every test (including mockito).

A new Trait `Transport` is introduced and `PyOci` is generic over `Transport`.
This allows swapping the `HttpTransport` in unittests in the future,
removing the need to mockito in a lot of cases.

Annotations have been structured a bit more.
- ImageIndex annotations will only include it's creation timestamp
- ImageIndex.manifests[] annotations will include package metadata
  we might need when listing/searching packages
- ImageManifest annotations will contain user-defined labels through
  `PyOci :: Label :: ` classifiers.

The `com.pyoci.sha256_digest` annotation is added containing the SHA256 digest
of the package blob.
This is a first step to make #160 work in an effective manner.

The SHA256 digest of the provided content is checked against the provided
`sha256_digest` in the request.

Cargo.toml

@@ -71,3 +71,4 @@ test-case = "3.3.1"
 tokio = { version = "1.43.0", features = ["test-util"]}
 bytes = "1.9.0"
 reqwest = { version = "0.12.12", default-features = false, features = ["stream"] }
+pretty_assertions = "1.4.1"

docs/design.md

@@ -7,6 +7,10 @@ Packages published through PyOCI use the `application/pyoci.package.v1` [artifac
 The image index gets tagged with the package version.
 This allows multiple build artifacts to be published to the same package version.
 
+`com.pyoci.sha256_digest` is added as an annotation in the `ImageIndex.manifests[]`
+containing the digest of the package blob.
+This is so we don't need to pull the manifest itself to get the digest of the package.
+
 ```json
 {
   "schemaVersion": 2,
@@ -22,7 +26,8 @@ This allows multiple build artifacts to be published to the same package version
         "os": "any"
       },
       "annotations": {
-        "org.opencontainers.image.created":"2024-11-20T20:23:36Z"
+        "org.opencontainers.image.created":"2024-11-20T20:23:36Z",
+        "com.pyoci.sha256_digest": "b7513fb69106a855b69153582dec476677b3c79f4a13cfee6fb7a356cfa754c0"
       }
     }
   ],
@@ -34,6 +39,11 @@ This allows multiple build artifacts to be published to the same package version
 
 ## Image Manifest
 
+When a package is published with `PyOci :: Label :: <key> :: <value>` classifiers,
+the key/value pair will be added to the ImageManifest annotations.
+
+'org.opencontainers.image.created' will always be added.
+
 ```json
 {
   "schemaVersion": 2,
@@ -52,6 +62,8 @@ This allows multiple build artifacts to be published to the same package version
     }
   ],
   "annotations": {
+    "org.opencontainers.image.description": "Published using PyOCI as part of the examples.",
+    "org.opencontainers.image.url": "https://github.com/allexveldman/pyoci",
     "org.opencontainers.image.created":"2024-11-20T20:23:36Z"
   }
 }