nip22 helper function to extract parent and root data

[dluvian]

Describe the enhancement

The nip65 module has a helper function to extract the relay list. I was hoping it was possible to do that for nip22 as well. Maybe two functions like nip22::extract_parent_data and nip22::extract_root_data which will return the k tag value, a|e|i|A|E|I tag value, relay/web page hint, and pubkey hint.

Use case

Implementing this every time is tedious. It would be nice if the library would provide this functionality.

Additional context

https://github.com/nostr-protocol/nips/blob/master/22.md#comment