Add support of Fon language (no supported in libicu)

[kelson42]

Fixes #1002

See

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 38.92%. Comparing base (e8b8c18) to head (733b027). Report is 211 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1013 +/- ## ======================================= Coverage 38.92% 38.92% ======================================= Files 58 58 Lines 3990 3990 Branches 2201 2201 ======================================= Hits 1553 1553 Misses 1090 1090 Partials 1347 1347 ```

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