Adds support for sqlite

[matthewpeterkort]

Adds Sqlite driver.

Uses https://pkg.go.dev/github.com/mattn/go-sqlite3#section-readme which enables most of the
psql code to be reused.

Grip server with Sqlite driver can be started with either:
grip server -c ./test/sqlite.yml or grip server -d sqlite if you want to use default DB file path

[bwalsh]

nice work!