Feature request: Query by unique fields (not just `id`)

[Arachnid]

It'd be useful to be able to do a query based on an ENS name, for instance, and have the subgraph code run namehash and transform the query before it's handed off to the execution engine.

That way, users can execute the more intuitive query {domain(name: "foo.eth") { ... }} instead of {domain(id: "0x..."){ ... }}.

[Jannis]

First thoughts: This would roughly require the following:

• support for non-id arguments for the singular ensDomain top-level query field
• a way to register argument transformations
  • this would likely be independent of the mappings / data sources
  • transformation functions could be defined in the manifest or in the schema
  • if they were defined the schema, we'd need a way in the manifest to describe which TypeScript file those functions are defined in