Configurable Azure authentication middleware for support of custom token providers

[kostrse]

Add support for parametrization into the Azure authentication middleware to support custom token providers which are not directly implemented in the SDK.

[andresmgot]

Can you elaborate on this issue @kostrse ? An example would be nice

[kostrse]

Currently AzureMiddleware implemented to call AzureTokenService and there's no way to customize this behavior. We're getting into a situation when different datasources may support different authentication types. ADX supports OBO which other datasources do not support etc.

So it would be great to be able to pass configuration to the AzureMIddleware during initialization to override its behavior

e.g. here

azhttpclient.AddAzureAuthentication(opts, { a custom list of token providers }, credentials, scopes)

To make this code block configurable.