Move all KPRepublic keyboards in the same directory

[GreatWizard]

This PR is similar to #5206 but we don't have to have fun with conflicts and it only moves boards into a subdirectory.

We should open smaller PR, extract from #5206, about the other changes (if they are still relevant) that are not related to the move of boards.

Description

To reduce clutter in the keyboards/ directory, this PR adds a kprepublic folder to collate all boards under one parent:

• bm16a
• bm16s
• bm43a
• bm60rgb
• cospad
• daisy
• jj4x4
• jj40
• jj50
• staryu
• xd0002
• xd0004
• xd60
• xd68
• xd75
• xd84
• xd87
• xd96

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Issues Fixed or Closed by This PR

close #5206

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[yanfali]

This one is further along #5206

[yanfali]

looks like a dupe.

[GreatWizard]

Yes it's the idea of #5206: only move directories and fix make commands
I think #5206 is too hard to rebase without headache and it's more than 1 year old: there are a lot of new kprepublic boards in qmk and changes that conflict.

[zvecr]

#5206 isnt too bad to rebase, has additional review context, plus i am still active on the project. The missing context is that the PR has dropped out of the last 2 merge windows due to internal discussions.

For now im going to close this one as a duplicate.