feat: refactor logging architecture to support other log collectors

[justprodev]

This pull request refactors and modernizes the remote_logging Dart package, expanding its capabilities from Loggly-only support to a more flexible, collector-based architecture for remote logging. It introduces a new abstraction for log collectors, adds support for Splunk, improves tag handling across platforms, and updates the API for easier extensibility and testing. The update also removes legacy code and updates documentation and tests to match the new structure.

Key changes:

Major Architecture and API Changes

• Introduced the LogCollector abstraction and refactored the logging pipeline to support multiple remote logging services, not just Loggly. The main entrypoint is now initRemoteLogging, which accepts any collector. (lib/src/model.dart [1] lib/src/remote_logging.dart [2] [3] lib/remote_logging.dart [4]
• Added HttpCollector as a base class for HTTP-based collectors, and implemented both LogglyCollector and new SplunkCollector classes for sending logs to Loggly and Splunk, respectively. (lib/src/remote/collectors/http_collector.dart [1] lib/src/remote/collectors/loggly_collector.dart [2] lib/src/remote/collectors/splunk_collector.dart [3]

Tag Handling and Platform Support

• Refactored tag handling to use platform-specific default tags via conditional exports, ensuring tags like the OS are automatically included. (lib/src/remote/tags/tags.dart [1] lib/src/remote/tags/impl/io_tags.dart [2] lib/src/remote/tags/impl/empty_tags.dart [3]
• Updated the tag aggregation logic in the logging pipeline to include log level, platform tags, logger name, and any custom tags. (lib/src/remote_logging.dart lib/src/remote_logging.dartL33-R57)

Deprecation and Cleanup

• Deprecated the old initLogging API in favor of initRemoteLogging, providing a backward-compatible wrapper for legacy usage. (lib/src/remote_logging.dart lib/src/remote_logging.dartR66-R96)
• Removed legacy Loggly-specific code and platform tag files, cleaning up the codebase. (lib/src/remote/loggly.dart [1] lib/src/remote/mobile_tags.dart [2]

Documentation and Testing

• Updated the README.md to reflect the new package name, API, and multi-collector support. (README.md README.mdL1-R15)
• Added new and updated tests for the new collector architecture and tag handling, and removed tests for deleted legacy code. (test/legacy_remote_logging_test.dart [1] test/loggly_collector_test.dart [2] test/loggly_test.dart [3]

Package Metadata

• Updated pubspec.yaml to reflect the new version (2.0.0), Dart SDK constraints, and description. (pubspec.yaml pubspec.yamlL2-R7)