dataconnect: Rename FirebaseDataConnectExperimental to ExperimentalFirebaseDataConnect

[dconeybe]

The previous PR #6424 named the "experimental" annotation FirebaseDataConnectExperimental; however, a more idiomatic name is ExperimentalFirebaseDataConnect, based on other similar classes from popular libraries, such as ExperimentalKotest, ExperimentalSerializationApi, and ExperimentalCoroutinesApi.

[github-actions]

Release note changes

The following release notes were modified. Please ensure they look correct.

Release Notes

firebase-dataconnect

### {{data_connect_short}} version 16.0.0-beta03 {: #data-connect_v16-0-0-beta03}

* {{changed}} Requires Data Connect emulator version 1.6.1 or later for code generation.

* {{feature}} QueryRef and MutationRef gain methods copy(), withDataDeserializer(),
  and withVariablesSerializer().
  (GitHub [#6424](//github.com/firebase/firebase-android-sdk/issues/6424){: .external})

* {{feature}} GeneratedConnector gains methods copy(), operations(), queries(),
  and mutations().
  (GitHub [#6424](//github.com/firebase/firebase-android-sdk/issues/6424){: .external})

* {{feature}} GeneratedQuery and GeneratedMutation gain methods copy(),
  withVariablesSerializer(), and withDataDeserializer().
  (GitHub [#6424](//github.com/firebase/firebase-android-sdk/issues/6424){: .external})

* {{feature}} GeneratedConnector, GeneratedQuery, and GeneratedMutation now
  must implement equals() to be a _logical_ comparsion, rather than just
  checking for _referencial_ equality using the `===` operator.
  (GitHub [#6424](//github.com/firebase/firebase-android-sdk/issues/6424){: .external})

* {{feature}} ExperimentalFirebaseDataConnect annotation added, and some
  APIs have been annotated with it, requiring applications that make use of
  these experimental APIs to opt-in using
  `@OptIn(ExperimentalFirebaseDataConnect::class)` to suppress warnings or
  errors related to using these experimental APIs.
  (GitHub [#6424](//github.com/firebase/firebase-android-sdk/issues/6424){: .external}) and
  (GitHub [#6433](//github.com/firebase/firebase-android-sdk/issues/6433){: .external})

[github-actions]

📝 PRs merging into main branch

Our main branch should always be in a releasable state. If you are working on a larger change, or if you don't want this change to see the light of the day just yet, consider using a feature branch first, and only merge into the main branch when the code complete and ready to be released.

[github-actions]

Vertex AI Mock Responses Check ⚠️

A newer major version of the mock responses for Vertex AI unit tests is available. update_responses.sh should be updated to clone the latest version of the responses: v5.1

[github-actions]

Test Results

   54 files  ±0     54 suites  ±0   2m 12s ⏱️ +16s
  515 tests ±0    514 ✅ ±0  1 💤 ±0  0 ❌ ±0 
1 030 runs  ±0  1 028 ✅ ±0  2 💤 ±0  0 ❌ ±0 

Results for commit a31edb7. ± Comparison against base commit 312d14a.