Migrate markdownlint + issue templates

[ashwinvaidya17]

Description

• Migrate to the same markdownlinter used by codacy.
• Use the new issue forms as issue templates.
• To see the fork for a working example - https://github.com/ashwinvaidya17/anomalib/issues/new/choose

Changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor (non-breaking change which refactors the code base)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist

• My code follows the pre-commit style and check guidelines of this project.
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing tests pass locally with my changes

[djdameln]

Thanks, looks good. Just one comment/question about the content of the bug report form.

[djdameln]

Thanks, I'm almost happy.