Add array type support for postgresql

[aliendrew]

Is your feature request related to a problem? Please describe.
Currently metaschema supports arrays and sets but metasql is unable to properly handle array types.

Describe the solution you'd like
Add postgresql array type support for metasql, so it can be properly handled.
I suggest the following:

points: {
  type: 'array',
  value: 'number',
  dims: [24, 32, 48],
  required: true,
}

to

"points" integer[24][32][48] NOT NULL

---

points: {
  type: 'array',
  value: 'number',
  dims: 3,
  required: true,
}

to

"points" integer[][][] NOT NULL

---

points: { array: 'number', length: 2 }

to

"points" integer ARRAY[2] NOT NULL

---

points: { array: 'number' }

to

"points" integer ARRAY NOT NULL

FYI:
https://www.postgresql.org/docs/current/arrays.html