Play Framework

feat(autotest): add --tests filter to run specific test classes headlessly

Previously the only way to run a subset of tests was the testrunner web UI
(/@tests); `play autotest` always ran the entire suite. Add a --tests=Class,...
flag so a single class (or a comma-separated set) can be exercised headlessly.

Plumbing mirrors the existing runUnit/webclientTimeout path:
  play autotest --tests=X  ->  -Ptests=X (generic shim rule, no shim change)
  ->  PlayAutotestTask.testClasses  ->  -DtestClasses=X on the FirePhoque JVM
  ->  FirePhoque filters the fetched /@tests.list before the lane split.

Matching is by simple name or FQCN (trailing .class optional); an ambiguous
simple name runs every match. Unknown names warn, and an all-miss filter exits
non-zero WITHOUT writing a result marker so a typo'd class fails the run instead
of masquerading as a green pass.

Filtering is client-side in FirePhoque, leaving the classification walk, routes,
and TestRunner controller untouched.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>