W-24224593: Select request authentication by path

[wmathurin]

Summary

• Let SalesforceSDKManager synchronously choose ui_sid Bearer authentication by request path when a DPoP access token is present.
• Default /lwr/ requests to ui_sid Bearer while keeping DPoP for other paths.
• Apply the policy consistently across REST, push, and DPoP nonce handling.
• Add coverage for policy, fallback, and authentication behavior and update DPoP documentation.

Test plan

• Focused SalesforceSDK unit tests: 109 passed.
• Additional authentication tests: 33 passed.
• assembleDebug: passed.