[.Net] Support tools for AnthropicClient and AnthropicAgent

[DavidLuong98]

Why are these changes needed?

Support tools for anthropic client.

• Update AnthropicClient to accept tools as an input
• Update AnthropicMessageConnector to process tools
• Wrote a few UT's for client and agent

Related issue number

Closes #2771

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://microsoft.github.io/autogen/docs/Contribute#documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[LittleLittleCloud]

Can you also update samples on how to use function call in AutoGen.Anthropic.Samples project.

maybe accomodate from one of these samples in anthropic api document

• https://docs.anthropic.com/en/docs/tool-use-examples

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[LittleLittleCloud]

@DavidLuong98 Is this good to merge in

[DavidLuong98]

@LittleLittleCloud yes