.Net: Anthropic - streaming

[Krzysztof318]

Motivation and Context

#5690

Description

Added streaming functionality and related tests.

@RogerBarreto @RogerBarret0

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 😄

[RogerBarreto]

Please fix the UnitTests.

[therealpaulgg]

not sure what else is going on with this PR but I have the following notes:

I wasn't able to get Vertex AI anthropic to work without the following changes:

• [JsonPropertyName("anthropic_version")] on the 'Version' attribute in AnthropicRequest
  • Reason: anthropic_version is required in the body for Vertex AI
• adding JsonIgnore to the 'Model' attribute in [JsonPropertyName("anthropic_version")]
  • Reason: Vertex AI doesn't allow extra attributes in the request, and the endpoint already contains the model as documented here

I would suggest making these simple changes but these will likely impact Anthropic and Bedrock implementations of this. Perhaps some additional work needs to be done to make things more compatible (maybe let's pass the type of service and not try to determine it implicitly?)

As for the failing unit tests I'm not sure what's going on there.

[Krzysztof318]

@RogerBarreto fixed