GitHub: Add issue templates

[RalphORama]

Issue templates:

• [ ] Request a new replacement
• [ ] Report an issue with a current replacement
• [ ] Request a new feature
• [ ] Report an issue with an existing feature
• [ ] Other

https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/configuring-issue-templates-for-your-repository

Don't think we need PR templates for now. Maybe something basic to notify people about required linting checks

[shoegaze]

New Feature Request template idea:

# Purpose

_What problems would this feature solve?_

# Scope

_What should this feature do?_
_What does this feature not do?_

# Screenshots/Mockups (optional)

_Any screenshots or mockups of the feature goes here_

# Implementation (optional)

_Ideas for implementing this feature_