I moved the custom index lookup, previously used in PyImportCollector to find
modules and packages, to PyModuleNameIndex, already utilized in other similar,
places such as PyModulePackageCompletionContributor. Two new methods where
introduced to the interface of PyModuleNameIndex for that. The first one
is a generalization of find(), allowing to re-use an existing search scope, and
the second finds modules by their fully qualified name in the same fashion as
it was done in PyClassNameIndex.findClass().
GitOrigin-RevId: 2de5821351eacf08ddc045454eea189b21fa1186
