refactor: update locking requirements for WorkThreadMain and SignPendingSigShares

Modified the WorkThreadMain function in signing.h and SignPendingSigShares in signing_shares.h to specify exclusive lock requirements. This change enhances thread safety by ensuring proper locking mechanisms are in place, preventing potential race conditions during concurrent operations.

Author: PastaPastaPasta

src/llmq/signing.h

@@ -242,7 +242,7 @@ class CSigningManager
     Mutex workMutex;
     std::condition_variable_any workCv;
     std::atomic<uint64_t> workEpoch{0};
-    void WorkThreadMain(PeerManager& peerman);
+    void WorkThreadMain(PeerManager& peerman) EXCLUSIVE_LOCKS_REQUIRED(!cs_pending, !cs_listeners);
 
 public:
     void StartWorkerThread(PeerManager& peerman);

src/llmq/signing_shares.h

@@ -491,7 +491,8 @@ class CSigSharesManager : public CRecoveredSigsListener
     void CollectSigSharesToAnnounce(const CConnman& connman,
                                     std::unordered_map<NodeId, Uint256HashMap<CSigSharesInv>>& sigSharesToAnnounce)
         EXCLUSIVE_LOCKS_REQUIRED(cs);
-    void SignPendingSigShares(const CConnman& connman, PeerManager& peerman);
+    void SignPendingSigShares(const CConnman& connman, PeerManager& peerman)
+        EXCLUSIVE_LOCKS_REQUIRED(!cs_pendingSigns);
     void WorkThreadMain(CConnman& connman, PeerManager& peerman);
     void NotifyWorker();
 };