feat: consider additional characters as comments (#45, #75)

[iliekturtles]

In addition to '#', also consider ';', '!', '$',
'%', '^', '&', '|', and ':' as comment characers.

This change does not read core.commentChar or core.commentString from a user's git config but instead uses the fixed list of characters above as a "short-term" fix for #45/#75.

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This is a rough start to support additional comment characters. All tests pass, but I expect there is additional work to clean things up.

• @ is removed from the list of characters used by Neovim.
• After actual testing with Neovim, it does read the user's git config. The static list above may only be for scissor detection.
• This change has effects on some of the tests that used to look for non-conventional commits starting with !, ...
• I haven't looked into what needs to change to ensure new translations inside the generated_comment_separator block are correct.