fix(windows): improve support for strings.xml

Fixes #4264.

The Android strings.xml format that we now use with Keyman Desktop has a
number of escapes that must be supported in order for text strings to be
rendered correctly, including: @, ?, ', ". Furthermore, positional
parameters have a slightly different format which we should transform on
load.

This change includes a unit test androidstringtokeymanlocalestring.