Update the language database from the canonical sources:
- It now includes most locales supported by Windows 10.
- It now also has the following attributes for each entry:
- BCP 47-like locale tag.
- Reference to canonical name for generic language entries.
- Language name in this language itself.
- Also add data file with list of language script identifiers and
aliases based on ISO 15924.
- And update genlang.py to handle all the new attributes and data.
Also move database-related methods of wxLocale to wxUILocale and
just redirect wxLocale methods to the new wxUILocale ones (they are
still preserved for compatibility).
Closes https://github.com/wxWidgets/wxWidgets/pull/2594
