This commit removes the migrations from channeldb and references those
in the migrations_01_to_11 package. This creates a one-way dependency on
the migrations. Future changes to channeldb won't be able to break
migrations anymore.
This commit is a direct copy of the complete channeldb package. It only
changes the package declaration at the top of every file. We make this
full copy so that review can be focused on the actual changes made.
Otherwise changes may drown in all the file moves.
Linting for the new package is disabled, as it contains lots of
pre-existing issues.
