Add static method to delete databases

[samwillis]

With v0.2 we will have this api as an options for specifying a VFS:

import { IdbFs } from "@electric-sql/pglite";
const pg = new PGlite({
  fs: new IdbFs("my-database")
})

We should add a delete static method to the VFS interface that deletes the database from the underlying storage:

import { IdbFs } from "@electric-sql/pglite";

IdbFs.delete('my-database')

[codewithcheese]

Would also like a method to clear the database. For unit testing re-initializing pglite every test is too slow. I am using a query to drop all tables in my afterEach but would prefer a more deterministic method.