Fix Microsoft OAuth token exchange returning invalid HTML/404

[aftabshuvo]

Summary

• Some hosting environments negotiate ALPN/TLS in a way that causes Microsoft's OAuth token endpoint (login.microsoftonline.com/.../oauth2/v2.0/token) to respond with an HTML error page (404) instead of the expected JSON, breaking Outlook connection setup and token refresh.
• Adds MicrosoftTokenTransport, a narrowly-scoped http_api_curl hook that disables CURLOPT_SSL_ENABLE_ALPN only for requests matching Microsoft's token host + path — no other provider's requests (Gmail, SMTP, Microsoft Graph, etc.) are touched.
• OAuth2Provider now registers this hook before the token request and additionally forces httpversion: 1.1 on the same request, both aimed at avoiding the connection negotiation that triggers the bad response.

Test plan

• Added integration test coverage in tests/integration/connection-behavior.php:
  • Confirms the Outlook token request is sent with httpversion: 1.1.
  • Confirms MicrosoftTokenTransport::isMicrosoftTokenUrl() matches only the Microsoft token endpoint (not the authorize endpoint, not Graph, not Google's token URL).
  • Confirms disableAlpnForMicrosoftTokenRequest() only disables ALPN for the Microsoft token URL and is a no-op for everything else.
• Manually verify against an environment that previously reproduced the HTML/404 error: connect an Outlook/Microsoft account and confirm the token exchange now returns JSON and the connection succeeds. (Not verified live in this session — recommend confirming before merge.)