Add schema syntax

[minenwerfer]

Aeria Lang is missing a way to define schemas that aren't collection schemas. In the example down below, track could be used, for example, inside a contract.

Syntax:

schema Track {
  name str
  artist str
  album str
}

Codegen:

export const track = {
  type: 'object',
  properties: {
    name: { type: 'string', },
    artist: { type: 'string', },
    album: { type: 'string', },
  },
}