Support for `CREATE RULE`

[seveibar]

(@seamapi is open to sponsor this repo/fix)

Example failing syntax:

CREATE RULE override_insert AS ON INSERT TO public.events DO INSTEAD (
    INSERT INTO public.events
    VALUES (NEW.*)
    RETURNING *
  );

  CREATE RULE parsing

  tests/ast-capabilities.test.ts:6

   5:   const statements =
   6:     parse(`CREATE RULE override_insert AS ON INSERT TO public.events DO INSTEAD (
   7:     INSERT INTO public.events

  Error thrown in test:

  Error {
    offset: 2,
    token: {
      col: 13,
      line: 1,
      lineBreaks: 0,
      offset: 12,
      text: 'override_insert',
      toString: Function tokenToString {},
      type: 'word',
      value: 'override_insert',
    },
    message: `Syntax error at line 1 col 13:␊
    ␊
    1      VALUES (NEW.*)␊
                   ^␊
    2      RETURNING *␊
    3    );␊
    Unexpected word token: "override_insert". I did not expect any more input. Here is the state of my parse table:␊
    ␊
        kw_view → %word ● ␊
        kw_recursive → %word ● ␊
        kw_global → %word ● ␊
        kw_local → %word ● ␊
        kw_unlogged → %word ● ␊
        kw_index → %word ● ␊
        kw_sequence → %word ● ␊
        kw_temporary → %word ● ␊
        kw_temp → %word ● ␊
        kw_function → %word ● ␊
        kw_extension → %word ● ␊
        kw_type → %word ● ␊
        kw_materialized → %word ● ␊
        kw_schema → %word ● ␊
    `,
  }

  › kw_schema → %word ●
  › Parser.feed (node_modules/nearley/lib/nearley.js:343:27)
  › _parse (node_modules/pgsql-ast-parser/src/parser.ts:110:16)
  › doParse (node_modules/pgsql-ast-parser/src/parser.ts:57:27)
  › parse (node_modules/pgsql-ast-parser/src/parser.ts:60:11)
  › <anonymous> (tests/ast-capabilities.test.ts:6:5)