wallet: allow to fetch the wallet descriptors for a given Script

We currently expose a method to get the signing providers, which allows
to infer a descriptor from the scriptPubKey. But in order to identify
"on" what descriptor a coin was received, we need access to the
descriptors that were imported to the wallet.

src/wallet/wallet.cpp

@@ -3311,6 +3311,18 @@ std::unique_ptr<SigningProvider> CWallet::GetSolvingProvider(const CScript& scri
     return nullptr;
 }
 
+std::vector<WalletDescriptor> CWallet::GetWalletDescriptors(const CScript& script) const
+{
+    std::vector<WalletDescriptor> descs;
+    for (const auto spk_man: GetScriptPubKeyMans(script)) {
+        if (const auto desc_spk_man = dynamic_cast<DescriptorScriptPubKeyMan*>(spk_man)) {
+            LOCK(desc_spk_man->cs_desc_man);
+            descs.push_back(desc_spk_man->GetWalletDescriptor());
+        }
+    }
+    return descs;
+}
+
 LegacyScriptPubKeyMan* CWallet::GetLegacyScriptPubKeyMan() const
 {
     if (IsWalletFlagSet(WALLET_FLAG_DESCRIPTORS)) {

src/wallet/wallet.h

@@ -839,6 +839,9 @@ public:
     std::unique_ptr<SigningProvider> GetSolvingProvider(const CScript& script) const;
     std::unique_ptr<SigningProvider> GetSolvingProvider(const CScript& script, SignatureData& sigdata) const;
 
+    //! Get the wallet descriptors for a script.
+    std::vector<WalletDescriptor> GetWalletDescriptors(const CScript& script) const;
+
     //! Get the LegacyScriptPubKeyMan which is used for all types, internal, and external.
     LegacyScriptPubKeyMan* GetLegacyScriptPubKeyMan() const;
     LegacyScriptPubKeyMan* GetOrCreateLegacyScriptPubKeyMan();