[chore] Split the bug template in two

[daenney]

Description

Based on the idea in #1438 (comment).

Have a separate template for:

• Frontend, with labels bug and frontend and requiring the browser field
• Regular/backend, for other bugs with only the bug label and removal of the browser field

Checklist

Please put an x inside each checkbox to indicate that you've read and followed it: [ ] -> [x]

If this is a documentation change, only the first checkbox must be filled (you can delete the others if you want).

• I/we have read the GoToSocial contribution guidelines.
• I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
• I/we have performed a self-review of added code.
• I/we have written code that is legible and maintainable by others.
• I/we have commented the added code, particularly in hard-to-understand areas.
• I/we have made any necessary changes to documentation.
• I/we have added tests that cover new code.
• I/we have run tests and they pass locally with the changes.
• I/we have run go fmt ./... and golangci-lint run.

[daenney]

@f0x52 like this?

[tsmethurst]

This looks handy!

[f0x52]

yep, thanks!