nostr: add support to NIP30 #974

Job	Run time
Format	7s
Build WASM (stable, -p nostr)	35s
Build WASM (stable, -p nostr-sdk)	36s
Build (stable, -p nostr)	2m 10s
Build no_std (nightly)	1m 37s
Build WASM (stable, -p nostr-js)	46s
Build (stable, -p nostr --no-default-features --features alloc)	31s
Build WASM (1.64.0, -p nostr)	4m 57s
Build (stable, -p nostr --no-default-features --features "alloc all-nips")	1m 40s
Build WASM (1.64.0, -p nostr-sdk)	6m 2s
Build (stable, -p nostr --features blocking)	2m 9s
Build WASM (1.64.0, -p nostr-js)	5m 3s
Build (stable, -p nostr-sdk)	3m 23s
Build (stable, -p nostr-sdk --no-default-features)	1m 45s
Build (stable, -p nostr-sdk --features blocking)	3m 38s
Build (stable, -p nostr-ffi)	2m 36s
Build (stable, -p nostr-sdk-ffi)	2m 39s
Build (1.64.0, -p nostr)	8m 3s
Build (1.64.0, -p nostr --no-default-features --features alloc)	4m 51s
Build (1.64.0, -p nostr --no-default-features --features "alloc all-nips")	5m 32s
Build (1.64.0, -p nostr --features blocking)	7m 36s
Build (1.64.0, -p nostr-sdk)	7m 4s
Build (1.64.0, -p nostr-sdk --no-default-features)	5m 46s
Build (1.64.0, -p nostr-sdk --features blocking)	6m 43s
Build (1.64.0, -p nostr-ffi)	8m 22s
Build (1.64.0, -p nostr-sdk-ffi)	6m 34s
	1h 40m 45s

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