Adding support for custom provider endpoints?

[axyr]

Would you consider a PR to add support for calling custom provider endpoints?

For example getting installed Ollama models:

https://github.com/ollama/ollama/blob/main/docs/api.md#list-local-models

We could start with simple calls like:

Prism::provider(Provider::Ollama)->call('api/tags');
Prism::provider(Provider::Ollama)->get('api/get-something', $options);
Prism::provider(Provider::Ollama)->post('api/any-endpoint', $options);

Or, if you would consider supporting full provider functionality:

Prism::provider(Provider::Ollama)->tags();

This could be a little more than unifying different provider text generation, but it would remove the need to install other packages to be able to communicate with AI providers.

[ChrisB-TL]

I missed this, but we recently did this with #219 and #273, which lay the groundwork for the latter type of endpoint.

Edit: if we were to do the former, I'd be tempted to just expose the client method on the providers, which provides a configured Http client.