[java-logging-logback] Update to use StackdriverJsonLayout

It would be good if https://github.com/GoogleCloudPlatform/spring-cloud-gcp/blob/main/spring-cloud-gcp-logging/src/main/java/com/google/cloud/spring/logging/StackdriverJsonLayout.java and related code from the spring-cloud-gcp library could be moved here without the small amount of spring specific depedencies.

It provides much higher quality stdout structured logs then what is currently available here.

**Is your feature request related to a problem? Please describe.**

We use some frameworks that are not spring based so can't use the spring cloud gcp logging for all our structured logs. The ones from spring cloud gcp includes things like support for httpRequest and labels metadata and tracing. As well as logger info, etc.

**Describe the solution you'd like**
Backport these to this library as there's only a couple of filters that require spring in that codebase and they could depend on this and still work.

**Describe alternatives you've considered**
Currently we're having to manually implementing something similar ourselves.