Implement support for GENERATED columns

[AnyhowStep]

Right now, it's just a bunch of TODOs with return undefined.

Before publishing, we need to implement this

[AnyhowStep]

Right now, to get metadata about a schema, we're using a bunch of regexes because SQLite doesn't give us enough information with the builtin pragmas and tables.

However...

CREATE TABLE StrayingFromGod (
    z VARCHAR 'qwewe' DEFAULT (
        'x INT AS (67); "y""y" BLOB AS (CAST(32 AS BLOB))'
    ) NOT NULL UNIQUE,
    "y""y" VARCHAR 'qwewe' 'NOT' NOT NULL AS (
        CAST(x AS VARCHAR) || (' is a ''good'' ' || ('value ' || 'I think'))
    ),
    x INT
);

Definitely need a proper parser, instead of regexes