Merge bitcoin/bitcoin#24313: Improve display address handling for external signer

4357158c47 wallet: return and display signer error (Sjors Provoost)
dc55531087 wallet: compare address returned by displayaddress (Sjors Provoost)
6c1a2cc09a test: use h marker for external signer mock (Sjors Provoost)

Pull request description:

  * HWI returns the requested address: as a sanity check, we now compare that to what we expected
     * external signer documentation now reflects that HWI alternatives must implement this check
  * both RPC and GUI will now return an error text, rather than just fail (the GUI even failed silently in some cases)

ACKs for top commit:
  brunoerg:
    ACK 4357158c47
  achow101:
    ACK 4357158c47

Tree-SHA512: 4f56edf3846745c8e7d08ef55cf29e8bb468256457149377c5f02da097931f9ca0c06bdbd856dc2385cde4fd11e4dc3b634c5a48814ff27f5562c8a25d43da93

src/wallet/interfaces.cpp

@@ -247,7 +247,7 @@ public:
         return value.empty() ? m_wallet->EraseAddressReceiveRequest(batch, dest, id)
                              : m_wallet->SetAddressReceiveRequest(batch, dest, id, value);
     }
-    bool displayAddress(const CTxDestination& dest) override
+    util::Result<void> displayAddress(const CTxDestination& dest) override
     {
         LOCK(m_wallet->cs_wallet);
         return m_wallet->DisplayAddress(dest);