Adding Ollama to Magentic One

[MervinPraison]

Why are these changes needed?

• Added support for a new chat completion client using the Ollama API (OllamaChatCompletionClient).
• Enhanced image handling with base64 encoding for the Ollama API.
• Updated environment-based client creation to accommodate the new Ollama client.

Related Issue Number

• No specific issue linked. You can mention an issue if applicable.

Checks

• [x] Documentation updated to reflect new changes.
• [x] Tested locally with Ollama

[MervinPraison]

@microsoft-github-policy-service agree

[jackgerrits]

This is great thank you! So it can be used in more places would you mind moving it to autogen-ext next to the other model clients?

[husseinmozannar]

This is awesome! As Jack mentioned, we'd love for this to be used broadly in autogen beyond magentic-one and in the AgentChat version of magentic-one

Quoting @jackgerrits : "Creating a custom model client is a matter of implementing this interface."

Happy to help on this

[ekzhu]

Possible to set up Ollama on CI action to test this?

[MervinPraison]

@jackgerrits @husseinmozannar @ekzhu Moved the Ollama Client to autogen-ext as per the suggestion