Whilst the former function does provide additional information, and
whilst the code base does juggle that information around, only the
suffixes themselves ever get used.

This eliminates usages of imp.find_module().

Doing so removes its usages of imp. For future reference, this is done by
running:

    swig -python sample.i

This does highlight though that, since swig's new generated files use
plain imports rather than imp/importlib, swig works fine without all our
special handling so dropping support for old style swig templates may be
the simplest way forward.

hook-pkg_without_hook_for_pkg.sub1.py contains checks that
pkg_without_hook_for_pkg.sub1 has a hook and pkg_without_hook_for_pkg
doesn't. Since PyInstaller lacks a nice standalone
find_hook(module_name) function, it uses imp.find_module() (which is not
how PyInstaller normally finds hooks) with the module search path being
the expected location of the hook plus PyInstaller's own hooks
subpackage.

importlib.util.find_spec() (the closet equivalent to imp.find_module()) is
unable to find any module with a `-` in it so an equivalent check is
impossible.

I consider a dumb `git ls-files | grep hook-pkg_without_hook_for_pkg.py`
to be all I need to convince me that `hook-pkg_without_hook_for_pkg.py`
doesn't exist so lets solve this problem by removing it.

When retrieving loader from importer/finder, prefer the PEP 451
`find_spec` to retrieve spec and loader from it, instead of using
PEP 302 `find_loader`. The latter has been obsolete for a while,
and became unavailabe on built-in importers/finders with python
3.12.