BeforeRequest autocmds are not cleaned up properly

[cmcaine]

Tridactyl version: 1.24.0pre6973-2414aba4
Firefox version: Mozilla Firefox 122.0.1
Operating system: win

• Brief description of the problem: Unlike other tridactyl autocommands, if you add multiple autocmds for the same pattern then they will all be run. I expected only the most recent autocmd to run.

• Steps to reproduce:

  1. :autocmd BeforeRequest https://example.com () => console.log(1)
  2. :autocmd BeforeRequest https://example.com () => console.log(2)
  3. Open the debugging inspector for tridactyl and visit example.com. Observe that both "1" and "2" are logged.

:autocmddelete unregisters only the most recent listener.

• Possible fixes:

Easiest would be to make src/background/webrequests.ts:registerWebRequestAutocmd unregister any pre-existing autocommand for the given event and pattern.