Big Bang Bot: Update CODEOWNERS

Action	User	Reason
Remove	@mark.nelson	Username is not present in either team or contributor whitelist.
Add	@daniel.stocum	User added from team charter mission team manifest
Add	@cschaefer	User added from team charter mission team manifest
Add	@matt.vasquez	User added from team charter mission team manifest
Add	@alfredodiaz53	User added from team charter mission team manifest
Add	@nbazzeghin	User added from team charter mission team manifest
Add	@dpritchettrm	User added from team charter mission team manifest

These changes were automatically generated based on the state stored in the team charter mission team manifest. If these changes are not expected, please refer to updating team charter manifest.