Merge #20861: BIP 350: Implement Bech32m and use it for v1+ segwit addresses

03346022d6 naming nits (Fabian Jahr)
2e7c80fb5b Add signet support to gen_key_io_test_vectors.py (Pieter Wuille)
fe5e495c31 Use Bech32m encoding for v1+ segwit addresses (Pieter Wuille)
25b1c6e13d Add Bech32m test vectors (Pieter Wuille)
da2bb6976d Implement Bech32m encoding/decoding (Pieter Wuille)

Pull request description:

  This implements [BIP 350](https://github.com/bitcoin/bips/blob/master/bip-0350.mediawiki):
  * For segwit v1+ addresses, a new checksum algorithm called Bech32m is used.
  * Segwit v0 address keep using Bech32 as specified in [BIP 173](https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki).

ACKs for top commit:
  Sjors:
    utACK 0334602
  jnewbery:
    utACK 03346022d6
  achow101:
    ACK 0334602
  fjahr:
    re-ACK 0334602
  benthecarman:
    ACK 03346022d6

Tree-SHA512: 4424cfd44869d813d6152fb3ed867b204036736bc2344a039b93700b6f36a43e9110478f138eb81c97c77ab27ecb776dada5ba632cb5a3a9d244924d2540a557

doc/bips.md

@@ -1,4 +1,4 @@
-BIPs that are implemented by Bitcoin Core (up-to-date up to **v0.21.0**):
+BIPs that are implemented by Bitcoin Core (up-to-date up to **v22.0**):
 
 * [`BIP 9`](https://github.com/bitcoin/bips/blob/master/bip-0009.mediawiki): The changes allowing multiple soft-forks to be deployed in parallel have been implemented since **v0.12.1**  ([PR #7575](https://github.com/bitcoin/bitcoin/pull/7575))
 * [`BIP 11`](https://github.com/bitcoin/bips/blob/master/bip-0011.mediawiki): Multisig outputs are standard since **v0.6.0** ([PR #669](https://github.com/bitcoin/bitcoin/pull/669)).
@@ -50,3 +50,4 @@ BIPs that are implemented by Bitcoin Core (up-to-date up to **v0.21.0**):
 * [`BIP 325`](https://github.com/bitcoin/bips/blob/master/bip-0325.mediawiki): Signet test network is supported as of **v0.21.0** ([PR 18267](https://github.com/bitcoin/bitcoin/pull/18267)).
 * [`BIP 339`](https://github.com/bitcoin/bips/blob/master/bip-0339.mediawiki): Relay of transactions by wtxid is supported as of **v0.21.0** ([PR 18044](https://github.com/bitcoin/bitcoin/pull/18044)).
 * [`BIP 340`](https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki) [`341`](https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki) [`342`](https://github.com/bitcoin/bips/blob/master/bip-0342.mediawiki): Validation rules for Taproot (including Schnorr signatures and Tapscript leaves) are implemented as of **v0.21.0** ([PR 19953](https://github.com/bitcoin/bitcoin/pull/19953)), without mainnet activation.
+* [`BIP 350`](https://github.com/bitcoin/bips/blob/master/bip-0350.mediawiki): Addresses for native v1+ segregated Witness outputs use Bech32m instead of Bech32 as of **v22.0** ([PR 20861](https://github.com/bitcoin/bitcoin/pull/20861)).

doc/release-notes-20861.md

@@ -0,0 +1,13 @@
+Updated RPCs
+------------
+
+- Due to [BIP 350](https://github.com/bitcoin/bips/blob/master/bip-0350.mediawiki)
+  being implemented, behavior for all RPCs that accept addresses is changed when
+  a native witness version 1 (or higher) is passed. These now require a Bech32m
+  encoding instead of a Bech32 one, and Bech32m encoding will be used for such
+  addresses in RPC output as well. No version 1 addresses should be created
+  for mainnet until consensus rules are adopted that give them meaning
+  (e.g. through [BIP 341](https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki)).
+  Once that happens, Bech32m is expected to be used for them, so this shouldn't
+  affect any production systems, but may be observed on other networks where such
+  addresses already have meaning (like signet).