Implement NIP-12 generic tag queries

[jimbojw]

NIP-12 describes an enhancement to NIP-01 tag queries beyond just #e and #p to any single character preceded by a pound sign.

Notes:

• Memorelay aggressively checks filters for conformance. Typings and tests will need to be updated to permit the new filter fields.
• Memorelay uses nostr-tools's matchFilter() function to test whether events match filters. Confirm that nostr-tools's implementation is NIP-12 compliant.

[jimbojw]

As of https://github.com/nostr-protocol/nips/commit/72bb8a128b2d7d3c2c654644cd68d0d0fe58a3b1, this has been rolled into NIP-01