Add rowid column to FTS5 tables

[ajeetdsouza]

Fixes #3901:

When creating a virtual table like so:

CREATE VIRTUAL TABLE my_fts USING fts5 (
    name,
    description,
    content = '',
    contentless_delete = 1,
    tokenize = 'porter'
);

SQLite automatically adds an extra rowid (int64) column to all fts5 virtual tables. However, this is not reflected in the schema. When I add a query like this:

-- name: InsertMyFTS :exec
INSERT INTO
    my_fts (rowid, name, description)
VALUES
    (?, ?, ?);

and call sqlc generate, I get this error:

query.sql:12:1: column "rowid" does not exist