Find Aspell dictionaries on Windows

Summary:
This feeds the sonnet aspell plugin some information to assist it in
locating dictionaries on Windows. It adds a heuristic which follows the
data location for applications installed using Craft on Windows.

Partial reintroduction of the hack in https://phabricator.kde.org/D9421
except this time it's relocateable

Test plan:
Without patch: No squiggly red lines (Sonnet debug-warns that no
dictionaries are found)
With patch: Squiggly red lines (Warnings gone)

Differential Revision: https://phabricator.kde.org/D10017