[Feature] Syntax highlighting for Erlang files

[ZeeWanderer]

SourceGit's built-in diff viewer does not syntax-highlight Erlang files:

• .erl
• .hrl
• .escript

Found a compatible TextMate grammar:
https://github.com/WhatsApp/erlang-language-platform/blob/main/editors/code/third-party/grammar/Erlang.plist

I think it's actively maintained.