GraphQL Uuid Filter Options

[gledis69]

Different types in graphql support different filter options:
e.g.

query {
	books(_filter: {id: {lt: 5 gt: 2}} title: {contains: "Book" notContains: "Great"})
	{
		...
	}
}

Currently, the uuid type is handled as String which supports:
eq, contains, notContains, startsWith, endsWith, neq, caseInsensitive, isNull

Most of these options are not meaningful for the uuid type. We can create custom scalar types quite easily and add a restricted set of filter options. Afaict, eq, gt, lt make sense for uuid.

@yorek @Aniruddh25 thoughts?