[persistence][spike] alembic migrations

[mikeldking]

Investigate the intersection between alembic (https://alembic.sqlalchemy.org/en/latest/front.html#installation) and sql alchamy and make sure they work together cleanly (how it tracks versions).

SqlAlchemy does create DDL so will have to figure out the separation of concerns.

https://www.sqlite.org/lang_altertable.html#otheralter
Sqlite quirks: https://alembic.sqlalchemy.org/en/latest/batch.html

Messy migration paths

• changing an index
• changing an enum