.Net: Voyageai integration

[fzowl]

Motivation and Context

Voyageai integration

Description

Added VoyageAI text, contextual and multimodal embeddings and reranker, similarly to other implementations.
MicrosoftDocs/semantic-kernel-docs#327

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[fzowl]

@microsoft-github-policy-service agree [company=VoyageAI]

[fzowl]

@moonbox3 @markwallace-microsoft Can you please take a look?

[rogerbarreto]

@fzowl, thanks for the contribution!

@microsoft-github-policy-service agree [company="VoyageAI"]

Please, provide the agreement without a > quote to enable the pipeline, thanks!

@fzowl, additionally I see that you are contributing in name of VoyageAI, given that I suggest creating any C# related official package in the https://github.com/voyage-ai org, something like github.com/voyage-ai/dotnet-sdk.

If that's your sole/individual contribution, suggest signing the CLA as an individual contributor and publishing the package in your repository using your own namespace e.g: FzOwl.SemanticKernel.VoyageAI.

We are very happy to share your contribution in the provided documentation PR pointing to the new source you select for the contribution package.

[fzowl]

@microsoft-github-policy-service agree company="VoyageAI"

[fzowl]

@rogerbarreto Yes, i'm contributing in the name of VoyageAI. What functions would you put to the official VoyageAI SDK package? In my PR, i tried to followed other integrations, like OpenAI or Google.
What do you think about the Python part of this PR?