Reverted wxFileSystem support in wxLocale.

Reverted wxFileSystem support in wxLocale.

The implementation was broken in numerous ways. URLs were corrupted in
search paths thanks to use of wxFileName for normalization. Lookup of
catalogs was broken, because ":" in URLs were interpreted as path
separators. Asserts occured because filenames were (incorrectly!)
interpreted as URLs.

Will replace with proper implementation.

See #8793, #11491.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63764 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775