Support Firebase SDK 8.x and PHP 8.3+

[jeromegamez]

• Added support for Firebase PHP SDK 8.x, and dropped support for version 7.x
• Raised minimum PHP support to 8.3
• Removed Dynamic Links integration (removed upstream)
• Removed legacy HTTP request logger config options (http_request_logger, http_request_debug_logger) that are no longer supported by the SDK
• Added per-project http_client_options support via Kreait\Firebase\Http\HttpClientOptions service ids
• Fixed cross-project option leakage by isolating ProjectFactory per configured project
• Removed container service Kreait\Firebase\Factory

Migration notes

• If you used http_request_logger / http_request_debug_logger, migrate to http_client_options + Guzzle middleware.
• If you customized DI internals:
  • Kreait\Firebase\Factory is no longer a container service
  • per-project factory service ids are now kreait_firebase.<project>.project_factory