Another commit in my quest to rid InterpreterBase from all higher
level object processing logic.
Additionally, there is a a logic change here, since `str.join` now
uses varargs and can now accept more than one argument (and supports
list flattening).
This really is more of a struct than a dict, as the types are disjoint
and they are internally handled, (ie, not from user input). This cleans
some things up, in addition I spotted a bug in the ModuleState where the
dict with the version and license is passed to a field that expects just
the version string.
Currently, EnvironmentVariablesObject is a strange
holder-that's-not-a-holder. This has implicaitons for things that expect
to get an EnvironmentVariables object, as we can't automatically
unholder it, and instead have to to manually do so. Now we can
automatically unholder it, which makes everything much nicer.
It should build the fallback subprject with default_library=static and
override the dependency for both static=True and static kwarg not given.
Fixes: #8050.