Add issue template to all TPO repos

We can add templates for how issues are being created to improve the information we have about a specific issue.

On gitlab templates: https://docs.gitlab.com/ee/user/project/description_templates.html

Proposal: https://gitlab.torproject.org/gaba/sandbox/-/issues/new

Core

• arti
• tpa
• tor
• applications
• community
• network health
• ux
• anti-censorship
• web
• metrics