gh-109162: Refactor Regrtest.main() (#109163)

gh-109162: Refactor Regrtest.main() (#109163)

* main() now calls _parse_args() and pass 'ns' to Regrtest
  constructor.  Remove kwargs argument from Regrtest.main().
* _parse_args() checks ns.huntrleaks.
* set_temp_dir() is now responsible to call expanduser().
* Regrtest.main() sets self.tests earlier.
* Add TestTuple and TestList types.
* Rename MatchTests to FilterTuple and rename MatchTestsDict
  to FilterTestDict.
* TestResult.get_rerun_match_tests() return type
  is now FilterTuple: return a tuple instead of a list.
  RunTests.tests type becomes TestTuple.