* Store a font name => font faces map
* Only list font names that have `NORMAL` and `BOLD` faces with
`Normal` stretch. This will give us defaults and fall-backs that are
guaranteed to always exist.
* Filter by stretch first, with `Normal` chosen as the always existing
default.
* Then only list font weights supported by the font name stretch
selected, for the normal and bold cases.
* When changing the font name selected, the stretch/weight options
will stay the same if supported by the new font name, or revert to
the always existing fall-backs.
Signed-off-by: Mohammad AlSaleh <CE.Mohammad.AlSaleh@gmail.com>