[Platform] Add support for Google vertex AI

[junaidbinfarooq]

Q	A
Bug fix?	no
New feature?	yes
Docs?	yes
Issues	#272
License	MIT

Changes proposed:

• Status: WIP
• The pr aims to add support for Google's Vertex AI
• Support is added for text generation and embeddings
• I created a separate directory inside the Bridge directory for the said bridge. Moving forward, we could either create a new namespace named Google and add two namespaces inside it, one each for Gemini and VertexAi, or we could simply keep VertexAi and remove the other, as this api already supports Gemini and more. Either way, Normalize Gemini vs Google #146 would be addressed.
• I exempted the use of api key from the implementation so far as VertexAi supports two auth mechanisms, Api keys and ADC ie., Application Default Credentials, but the former is recommended for testing while the latter is recommended for production, IIRC though it does need to install gCloud on the server and locally too (if verifying the behavior without an api key). Though I am yet to check it out programmatically, a curl request from the CLI does work with ADC.
• More information can be found at https://cloud.google.com/vertex-ai/generative-ai/docs

[chr-hertel]

Please move it to require-dev and add a check for the class existence to the implementation, like in the Bedrock one for example:

ai/src/platform/src/Bridge/Bedrock/PlatformFactory.php

Lines 37 to 39 in 11ef98f

	if (!class_exists(BedrockRuntimeClient::class)) {
	throw new RuntimeException('For using the Bedrock platform, the async-aws/bedrock-runtime package is required. Try running "composer require async-aws/bedrock-runtime".');
	}

[aszenz]

Suggested change

	throw new RuntimeException('For using the Bedrock platform, the google/auth package is required. Try running "composer require google/auth".');
	throw new RuntimeException('For using the Vertex AI platform, google/auth package is required for authentication via application default credentials. Try running "composer require google/auth".');

[junaidbinfarooq]

I did it already.
Pushing the change in a few moments.

[faizanakram99]

lgtm, ship it

[junaidbinfarooq]

lgtm, ship it

Docs and AI bundle integration need to be added first.