gh-108834: regrtest reruns failed tests in subprocesses

[vstinner]

Rename --verbose2 option (-w) to --rerun. Keep --verbose2 as a deprecated alias.

Fix statistics in regrtest summary.

Changes:

• Add RunTests class.
• Add TestResult.get_rerun_match_tests() method
• Rewrite code to serialize/deserialize worker arguments as JSON using a new WorkerJob class.
• Fix stats when a test is run with --forever --rerun.
• If failed test names cannot be parsed, log a warning and don't filter tests.
• test_regrtest.test_rerun_success() now uses a marker file, since the test is re-run in a separated process.
• Add tests on normalize_test_name() function.

• Issue: regrtest should re-run failed tests in subprocesses #108834