Sentry Structured Logging for Ruby

[AbhiPrasad]

https://develop.sentry.dev/sdk/telemetry/logs/

Sentry is adding support for structured logging. Let's add it to the Ruby SDK!

1. Define the logs protocol and log envelope item in the SDK
2. Add the Public API (SDK options and methods) as per the docs
3. Make sure the the SDK follow the documented behavior
4. Attach default attributes to the SDK as per docs
5. Instrument popular logging libraries to send logs to Sentry. SDK maintainers can best decide what they should support, but we should aim to get std lib Logger (and I guess ActiveSupport::Logger) automatically instrumented.
6. Create a GH discussion that contains instructions for setting up the SDK in your repo. Eventually this will be moved into the primary docs. See the JS SDK's GH discussion for inspiration.