bpo-35233: Fix _PyMainInterpreterConfig_Copy() (GH-10519)

* Fix _PyMainInterpreterConfig_Copy():
   copy 'install_signal_handlers' attribute
* Add _PyMainInterpreterConfig_AsDict()
* Add unit tests on the main interpreter configuration
  to test_embed.InitConfigTests
* test.pythoninfo: log also main_config
6 files changed