feat: add/use RFC3339 fields in requests

Timestamp fields that store time as milliseconds since epoch are
being replaced by fields that store it as a RFC 3339 string.

This commit:
- Removes POST /feedbacks `timestamp` field, replacing it with
`occurred_at`. Removal is possible because this field is not in
the public API.
- Add `collected_at` to POST /signups' `additional_locations`. This
field should be used instead of the existing `timestamp`.

src/main/java/com/incognia/api/IncogniaAPI.java

@@ -408,14 +408,14 @@ public void registerFeedback(
 
   public void registerFeedback(
       FeedbackEvent feedbackEvent,
-      Instant timestamp,
+      Instant occurredAt,
       FeedbackIdentifiers identifiers,
       boolean dryRun)
       throws IncogniaException {
     PostFeedbackRequestBody requestBody =
         PostFeedbackRequestBody.builder()
             .event(feedbackEvent)
-            .timestamp(timestamp.toEpochMilli())
+            .occurredAt(occurredAt)
             .installationId(identifiers.getInstallationId())
             .sessionToken(identifiers.getSessionToken())
             .accountId(identifiers.getAccountId())

src/main/java/com/incognia/common/AdditionalLocation.java

@@ -3,10 +3,14 @@
 import lombok.Builder;
 import lombok.Value;
 
+import java.time.Instant;
+
 @Value
 @Builder
 public class AdditionalLocation {
   Double lat;
   Double lng;
+  @Deprecated
   Long timestamp;
+  Instant collectedAt;
 }

src/main/java/com/incognia/feedback/PostFeedbackRequestBody.java

@@ -3,11 +3,13 @@
 import lombok.Builder;
 import lombok.Value;
 
+import java.time.Instant;
+
 @Value
 @Builder
 public class PostFeedbackRequestBody {
   FeedbackEvent event;
-  Long timestamp;
+  Instant occurredAt;
   String accountId;
   String externalId;
   String installationId;

src/test/java/com/incognia/api/IncogniaAPITest.java

@@ -556,7 +556,7 @@ void testRegisterFeedback_whenDataIsValid(boolean dryRun) {
             .signupId(signupId)
             .accountId(accountId)
             .event(FeedbackEvent.ACCOUNT_TAKEOVER)
-            .timestamp(timestamp.toEpochMilli())
+            .occurredAt(timestamp)
             .build());
     mockServer.setDispatcher(dispatcher);
     client.registerFeedback(