feat: export more types

[florian-lefebvre]

Working on withastro/astro#14980 I found I need more types from unifont, that are currently not exported. Otherwise TS throws errors like Return type of exported function has or is using name ResolveFontResult from external module but cannot be named.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.03%. Comparing base (95583aa) to head (beb72e8).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #305   +/-   ##
=======================================
  Coverage   99.03%   99.03%           
=======================================
  Files          11       11           
  Lines         516      516           
  Branches      132      132           
=======================================
  Hits          511      511           
  Misses          5        5           

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