Process the token claims at the end of msal scheme. call

[tjadevries]

Implements feature request as described in issue #53

[Copilot]

Pull Request Overview

This PR implements feature request #53 by adding support for custom token claims processing in the MSAL authentication scheme. The implementation allows for processing of token claims at the end of authentication with an optional callback function.

• Added a claims_processing parameter to allow custom handling of token claims
• Introduced a default_claims_processing function that extracts user info from token claims
• Updated the authentication flow to call the claims processing function after token validation

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
fastapi_msal/security/msal_scheme.py	Added claims processing functionality with default implementation and callback support
fastapi_msal/security/init.py	Exported the new default_claims_processing function
fastapi_msal/auth.py	Updated MSALAuth class to accept and pass through claims_processing parameter

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