Adds ComposedSchema to store schema composed schemas
This is needed if generator need to detect the presence of composed schemas or iterate over them and generate code/classes with the composed schema info.

This is a replacement for:

• Add oneOfProps, allOfProps, anyOfProps to Codegen model #10231
• Add extension to store oneOf/anyOf/allOf objects as full properties #9977

And allows us to use #getComposedSchemas to test for the presence of composed schemas
And then we can use getAllOf, getOneOf, getAnyOf to access the lists of CodegenProperties
@wing328
@zippolyte
If you want different names for these classes and methods let me know.

This adds missing composed schema info and is a feature implementation for:

• [BUG] Schema info is not being stored in core java classes for five use cases #7613

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package 
  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh
  

  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  For Windows users, please run the script in Git BASH.
• File the PR against the correct branch: master (5.3.0), 6.0.x
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.