Fail on javadoc errors and fix remaining javadoc errors

[HannesWell]

Fix all javadoc errors except for the packages org.eclipse.pde.internal.build.publisher and org.eclipse.pde.internal.core.ant which contain only ANT task sources and therefore require special class-path configuration that I wasn't able to properly replicate for the javadoc build.

To avoid javadoc errors in the future also fail the build on javadoc errors.

Should fix https://github.com/eclipse-pde/eclipse.pde/issues/1392.

This also contains the commit/changes from the following PRs with the requested changes applied:

• https://github.com/eclipse-pde/eclipse.pde/pull/1394
• https://github.com/eclipse-pde/eclipse.pde/pull/1393

[github-actions[bot]]

Test Results

   285 files  ±0     285 suites  ±0   47m 42s :stopwatch: - 2m 28s  3 581 tests ±0   3 505 :white_check_mark: ±0   76 :zzz: ±0  0 :x: ±0  10 935 runs  ±0  10 704 :white_check_mark: ±0  231 :zzz: ±0  0 :x: ±0 

Results for commit 3c742e22. ± Comparison against base commit 339bd954.