improve bug report and feature request issue templates

[mashb1t]

This PR adds required fields and more structure with the goal of making issue handling easier and to streamline bug reports and feature requests.

EDIT: you can test the templates here: https://github.com/mashb1t/Fooocus/issues/new/choose

@lllyasviel I'd really like to not only contribute to the project with PRs but also with issue cleanup, as the number of open issues is increasing more and more (currently 575). Would it be possible to be added to the triage role (no write access) or as contributor? Once more emphasising that i don't need write access or want take over code ownership at all. Thank you and looking forward to your feedback!

@MoonRide303 @daswer123 sorry for pinging you, but i assume you're also maintainers(?), maybe you can review this PR to make it easier for @lllyasviel to return in January. Thanks!