feat(telemetry): middleware for propagating telemetry from requests

[LucasAlvesSoares]

Description

Introduced support to middlewares for enriching auto instrumentation as well as a built-in A2A Starlette middleware for IAS info

Type of Change

Please check the relevant option:

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Code refactoring
• Dependency update

How to Test

Describe how reviewers can test your changes:

1. Create a StarletteA2A-based agent
2. Create the newly implemented middleware
3. Add this middleware to auto instrumentation
4. Send a request with an authorization header with a jwt containing user_uuid and sap_gtid claims
5. Watch telemetry contain the respective attributes

Checklist

Before submitting your PR, please review and check the following:

• I have read the Contributing Guidelines
• I have verified that my changes solve the issue
• I have added/updated automated tests to cover my changes
• All tests pass locally
• I have verified that my code follows the Code Guidelines
• I have updated documentation (if applicable)
• I have added type hints for all public APIs
• My code does not contain sensitive information (credentials, tokens, etc.)
• I have followed Conventional Commits for commit messages

[jeanscherf]

LGTM