Automatically export database backed splits before a config import

Problem/Motivation

Splits can be configured to use a database table for their storage, the utility of this is that one can split configuration without exporting it to the file system and thus make it work a bit like config ignore. But extra steps are required during a deployment. In particular the splits have to be manually exported before a config import. This decreases the utility a bit because it makes it more difficult.

Proposed resolution

In a drush command hook export the database backed splits before the config import command is run.

Remaining tasks

Implement

User interface changes

Explanation on the storages of this new feature.

API changes

none

Data model changes

none