Replace any named UNIQUE indices in the accounts tables and replace with
named ones. This is for a future where we want to be able to edit these
indices without having to drop the table.
It is fine for us to just edit these tables since these are not
available in "prod" yet.
This commit adds the boilerplate code we will need in order to start
using SQL backed stores (namely sqlite and postgres) for our DB backend.
NOTE that this has been copied from the taproot-assets repo.
This commit also contains the sqlc.yaml file, the `make sqlc` command
and the script for generating sqlc code. This must be done in this
commit as the script only works if there are queries to generate from.
