FK and unique constraints need to sit at table-level

[MandarinDuck]

These properties need to sit outside of the column property or they won't work for composite column constraints.

mojap-metadata/mojap_metadata/metadata/specs/table_schema.json

Lines 33 to 84 in 9c43fb8

	"foreign_key": {
	"type": "array",
	"title": "The list of foreign key relationships this column has, if any",
	"default": [],
	"examples": [
	[
	{
	"table": "",
	"columns": []
	}
	]
	],
	"items": {
	"anyOf": [
	{
	"type": "object",
	"default": {},
	"examples": [
	{
	"table": "",
	"columns": []
	}
	],
	"required": [
	"table",
	"columns"
	],
	"properties": {
	"table": {
	"type": "string",
	"title": "The table name",
	"default": "",
	"examples": [
	""
	]
	},
	"columns": {
	"type": "array",
	"title": "The list of column names",
	"default": []
	}
	},
	"additionalProperties": true
	}
	]
	}
	},
	"unique": {
	"type": "boolean",
	"title": "Specifies if the values in the column must be unique",
	"default": false
	},