Add support for schema providers for generic classes

[tilgalas]

Permits to infer schemas and row conversion functions for generic classes for schema providers extending GetterBasedSchemaProvider, see new test cases for examples of such inference. The PR is mostly about passing on the TypeDescriptors where previously the mechanism used raw Classes, and making use of them to resolve generic type variables to concrete types.

This change was discussed in this design doc's section called Generic Types

---

Thank you for your contribution! Follow this checklist to help us incorporate your contribution quickly and easily:

• [ ] Mention the appropriate issue in your description (for example: addresses #123), if applicable. This will automatically add a link to the pull request in the issue. If you would like the issue to automatically close on merging the pull request, comment fixes #<ISSUE NUMBER> instead.
• [ ] Update CHANGES.md with noteworthy changes.
• [ ] If this contribution is large, please file an Apache Individual Contributor License Agreement.

See the Contributor Guide for more tips on how to make review process smoother.

To check the build health, please visit https://github.com/apache/beam/blob/master/.test-infra/BUILD_STATUS.md

GitHub Actions Tests Status (on master branch)

See CI.md for more information about GitHub Actions CI or the workflows README to see a list of phrases to trigger workflows.

[github-actions[bot]]

Checks are failing. Will not request review until checks are succeeding. If you'd like to override that behavior, comment assign set of reviewers

[tilgalas]

Run Java PreCommit

[tilgalas]

Run Java PreCommit

[chamikaramj]

assign set of reviewers

[github-actions[bot]]

Assigning reviewers. If you would like to opt out of this review, comment assign to next reviewer:

R: @damondouglas for label java. R: @shunping for label io.

Available commands:

• stop reviewer notifications - opt out of the automated review tooling
• remind me after tests pass - tag the comment author after tests pass
• waiting on author - shift the attention set back to the author (any comment or push by the author will return the attention set to the reviewers)

The PR bot will only process comments in the main thread (not review comments).

[tilgalas]

closing the PR to split it into smaller ones