Use regex matching for modules that should always fork

[Nihlus]

The current logic used to match module names that should always fork has room for improvement. As exemplified by the recent addition of the FreeIPA modules, which was a rather long list, the ability to use patterns instead of exact string matches would improve readability and long-term maintainability of the mechanism.

This PR changes the module set into a set of regular expression strings and compiles them into a single joint regex that we then use to match against the module name.

[moreati]

Notes/random thoughts

• Agree the long frozenset is ugly and too brittle
• If we're changing the interface/meaning of the attribute ALWAYS_FORK_MODULES, then it's probably not worth keeping.
• Perhaps hide implementation details behind a method like _module_requires_fork(self, modname)
• Could it become runtime configurable? E.g. Ansible plugin option, environment variable

Sorry for the long wait to look at this. I plan to give it more attention in the next few weeks