meta/files/bitbake-setup.schema.json: move to bitbake repo

meta/files/bitbake-setup.schema.json: move to bitbake repo

The schema for bitbake-setup configurations was provisionally
placed into oe-core, as it is an extension of an earlier
layer setup schema, but with bitbake-setup becoming the primary
way to set up layers, it makes sense to maintain both schemas
in bitbake, so that any updates and tweaks can be done in
lockstep in a single repository.

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>