Research: Plugin hook for alternative database connections

[simonw]

The Database class is a natural looking fit for a plugin hook to load custom database connections... potentially even databases other than SQLite. DuckDB (refs #968) could make for a great starting point, since it looks very compatible with the existing SQLite code.

The real win would be if this could lead to running Datasette against PostgreSQL. I made some initial explorations in that direction a while ago in #670.

[simonw]

DuckDB has a read-only mechanism: https://duckdb.org/docs/api/python

import duckdb
con = duckdb.connect(database="/tmp/blah.db", read_only=True)

[simonw]

This is a duplicate of #1193.