GraphQL Uuid Filter Options

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