* Add ClientImportOperation and remove an unused enum
* set_aux to insert_aux so that it can be called multiple times
* [WIP] All basic designs of lock_import_and_run
* [WIP] `apply_block` and `apply_aux` implementation
* Update client db with the new interface
* Always make sure we reset importing_block back to None
* Address grumbles
`apply_block` should be pub
* Add comments on insert_aux
* Fix compile