Azure support: Auto

[ctjlewis]

Rate limit headers don't behave exactly the same as OpenAI's API, no time to add right now, good first PR or will get to it later.

From Azure:

    MAIN | 2024-03-02 13:35:10 | HEADERS | {'cache-control': 'no-cache, must-revalidate', 'content-length': '831', 'content-type': 'application/json', 'access-control-allow-origin': '*', 'apim-request-id': 'bb943c68-99ed-46ab-bda9-a5efbdf5897a', 'strict-transport-security': 'max-age=31536000; includeSubDomains; preload', 'x-content-type-options': 'nosniff', 'x-ms-region': 'North Central US', 'x-ratelimit-remaining-requests': '79', 'x-ratelimit-remaining-tokens': '61353', 'x-accel-buffering': 'no', 'x-request-id': '3a8b1a44-a02c-4a07-b51d-1c88acec4c4f', 'x-ms-client-request-id': 'bb943c68-99ed-46ab-bda9-a5efbdf5897a', 'azureml-model-session': 'd008-20240215231538', 'date': 'Sat, 02 Mar 2024 21:35:09 GMT'}

Seems wholly reliant on x-ratelimit-remaining-requests, where the library relies on OpenAI's x-ratelimit-limit-tokens headers, since their remaining-requests and remaining-tokens values are cached for long periods and do not update.