This is gated behind a new option in `podman system migrate`,
`--migrate-db`.
The basic logic is simple:
* Podman is already configured to use BoltDB
* Open a new, fresh SQLite database to write into
* Migrate all database contents as they exist in BoltDB, to
SQLite.
** Do this as simply as possible: grab the object from the old DB
and write it into the new DB using the standard Add and Save
functions.
* Set the new database in the Runtime, close the old one.
* Move the old database file so it won't be reused
* Show a warning if the user explicitly configured BoltDB in
containers.conf
Our ability to test complex migration scenarios is limited, but
this should handle simple migrations easily.
Fixes#27628
Signed-off-by: Matt Heon <matthew.heon@pm.me>
b320fbcaff