.Net: Add output dimensions to VertexAIEmbeddingGenerator to make it feature parity with GoogleAI service

[abbottdev]

Describe the bug
There is a split between the behaviour of the GoogleAI and VertexAI support. When output dimensions were added they were only added to the GoogleAI implementation, not the VertexAI implementation.

Also of note, VertexAIEmbeddingGenerator is using obsolete code (VertexAITextEmbeddingGenerationService and should be migrated to have the implementation in VertexAIEmbeddingGenerator present in the same class.

Platform

• Language: C#
• Source: main
• AI model: Google Vertex

[markwallace-microsoft]

@abbottdev Thanks for creating this issue. Are you interested in creating a fix?

[abbottdev]

Happy to contribute if needed @markwallace-microsoft - I'm looking at the implementation and we hit the HTTP APIs for Gemini directly. What's the direction of travel here? There's Google SDKs which could wrap up the rest API calls.

I've been using this as a temporary workaround (disclaimer, not my code) which seems to be working well:
https://github.com/AustinWise/AiExtensionsForVertexAi/blob/2d9064f5f251fb4e6b045aa72601f6572b89a880/src/AWise.AiExtensionsForVertexAi/VertexAiEmbeddingGenerator.cs#L6

So question would be, is there appetite to use the Google provided SDKs instead of direct HTTP calls? I think it'd make maintaining API compatibility easier (IMO).