Add tests to dogfood compiling JCT within JCT

[ascopes]

Adds an acceptance test to "dogfood" compile JCT within itself.

This tests that the management of sources within JCT is close enough
to the regular javac file management implementation to enable compiling
a project with over 100 interlinked classes and transitive JPMS
dependencies into a RAM disk location.

[github-actions]

Test Results

  1 592 files    1 592 suites   0s ⏱️
21 456 tests 21 444 ✔️ 12 💤 0 ❌
21 720 runs  21 708 ✔️ 12 💤 0 ❌

Results for commit bd4b7dd.

[codecov-commenter]

Codecov Report

Merging #336 (bd4b7dd) into main (aa5ac84) will not change coverage.
The diff coverage is n/a.

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  Lines        2700     2700           
  Branches      225      225           
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  Hits         2135     2135           
  Misses        509      509           
  Partials       56       56