Migrate VertexAI serialization to be localized

[emilypgoogle]

There are some considerations to how this should be finalized. Current implementation details that I've decided on which we can change:

• Based on the example doc, all classes Foo have been renamed InternalFoo
• All internal serialization classes, where relevant, are moved to inner classes of their API counterparts
• All classes only used as child fields for serialization classes have been moved to inner classes of those classes
• All toPublic and toInternal methods on API and serialization classes have been moved inside of those classes and conversions.kt has been mostly emptied.
• A few serialization classes do not have API equivalents and are left in a Types.kt file

Possible changes:

• Change all InternalFoo classes to have the same name, referenced as Foo.Internal rather than Foo.InternalFoo. This will probably make the codebase feel cleaner, but I'll wait for opinions on it
• Move serialization only classes out of the internal serialization classes, either to inner classes of the API classes or top level classes themselves.
• For classes that have serializers, rename serializers from InternalFooSerializer to Serializer for example Foo.InternalFoo.Serializer or Foo.Internal.Serializer instead of Foo.InternalFoo.InternalFooSerializer or Foo.Internal.InternalFooSerializer

[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: v5.3

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Coverage Report ¹

Affected Products

No changes between base commit (8e61ec2) and merge commit (324baa9).

Test Logs

• Merge (324baa9): https://github.com/firebase/firebase-android-sdk/actions/runs/12837874299

1. https://storage.googleapis.com/firebase-sdk-metric-reports/tbmNiWtvxk.html

[github-actions]

Test Results

0 files   -    64  0 suites   - 64   0s ⏱️ - 1m 12s
0 tests  -   542  0 ✅  -   541  0 💤  - 1  0 ❌ ±0 
0 runs   - 1 084  0 ✅  - 1 082  0 💤  - 2  0 ❌ ±0 

Results for commit bbfaa1e. ± Comparison against base commit 8e61ec2.

[daymxn]

This doesn't currently compile, as there's some imports and usages that need to be updated. Like:

- private fun InternalGenerateContentResponse.validate()
+ private fun GenerateContentResponse.InternalGenerateContentResponse.validate()

Also, (and this probably a convo for @rlazo too), any reason we want the fully qualified names over something like Internal?

Current:

public class FunctionDeclaration(
  internal val name: String,
  internal val description: String,
  internal val parameters: Map<String, Schema>,
  internal val optionalParameters: List<String> = emptyList(),
) {
  internal val schema: Schema =
    Schema.obj(properties = parameters, optionalProperties = optionalParameters, nullable = false)

  internal fun toInternal() =
    InternalFunctionDeclaration(name, "", schema.toInternal())

  @Serializable
  internal data class InternalFunctionDeclaration(
    val name: String,
    val description: String,
    val parameters: Schema.InternalSchema
  )
}

With internal naming:

public class FunctionDeclaration(
  internal val name: String,
  internal val description: String,
  internal val parameters: Map<String, Schema>,
  internal val optionalParameters: List<String> = emptyList(),
) {
  internal val schema: Schema =
    Schema.obj(properties = parameters, optionalProperties = optionalParameters, nullable = false)

  internal fun toInternal() =
   Internal(name, "", schema.toInternal())

  @Serializable
  internal data class Internal(
    val name: String,
    val description: String,
    val parameters: Schema.InternalSchema
  )
}

So its usage would be like this:

- FunctionDeclaration.InternalFunctionDeclaration(...)
+ FunctionDeclaration.Internal(...)