[3.12] gh-117860: Add tests for resolving names when import rebind names (GH-118176...

[3.12] gh-117860: Add tests for resolving names when import rebind names (GH-118176) (GH-118432)

Add tests for "import", pkgutil.resolve_name() and unittest.mock.path()
for cases when "import a.b as x" and "from a import b as x" give
different results.
(cherry picked from commit c0eaa232f63a62e0e0408911ab5f118dca2af607)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>