fix: Speech service API issue fixed

[AjitPadhi-Microsoft]

Purpose

• This pull request updates how Azure Speech tokens are acquired, adding support for Azure RBAC authentication in addition to key-based authentication. The main logic in speech_config is updated to use a managed identity and AAD token when AZURE_AUTH_TYPE is set to "rbac". Corresponding tests are refactored to cover this new authentication flow.

Authentication logic updates:

• code/create_app.py: The speech_config function now supports both key-based and RBAC (Azure Active Directory) authentication. When AZURE_AUTH_TYPE is "rbac", it retrieves an AAD token using a managed identity and uses it to request a speech token, instead of a subscription key.

Test updates:

• code/tests/test_create_app.py: The test setup (env_helper_mock) and the test_returns_speech_token_using_rbac test are updated to mock the new RBAC authentication flow, including checking that the correct credential and token retrieval calls are made. [1] [2] [3]

Does this introduce a breaking change?

• Yes
• No

How to Test

• Get the code

git clone [repo-address]
cd [repo-name]
git checkout [branch-name]
npm install

• Test the code

What to Check

Verify that the following are valid

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