Merge #17564: rpc: Use mempool from node context instead of global

fa8e650b52 rest: Use mempool from node context instead of global (MarcoFalke)
fa660d65d7 node: Use mempool from node context instead of global (MarcoFalke)
facbaf092f rpc: Use mempool from node context instead of global (MarcoFalke)

Pull request description:

  Currently they are identical, but in the future we might want to turn
  the mempool into a unique_ptr. Replacing the global with the mempool
  pointer from the node context simplifies this step.

ACKs for top commit:
  jnewbery:
    Code review ACK fa8e650b5
  ryanofsky:
    Code review ACK fa8e650b52, Only the discussed REST server changes since the last review.

Tree-SHA512: 0836f3f39cf90306455962918446e5f8612e88c32072b92afc30929aea1f17430bbda0e2b3668d36c9d6b97d63a93cf4903185194571108642b7bf5a39b89125

src/rpc/rawtransaction.cpp

@@ -636,6 +636,7 @@ static UniValue combinerawtransaction(const JSONRPCRequest& request)
     CCoinsView viewDummy;
     CCoinsViewCache view(&viewDummy);
     {
+        const CTxMemPool& mempool = EnsureMemPool();
         LOCK(cs_main);
         LOCK(mempool.cs);
         CCoinsViewCache &viewChain = ::ChainstateActive().CoinsTip();
@@ -758,7 +759,7 @@ static UniValue signrawtransactionwithkey(const JSONRPCRequest& request)
     for (const CTxIn& txin : mtx.vin) {
         coins[txin.prevout]; // Create empty map entry keyed by prevout.
     }
-    FindCoins(coins);
+    FindCoins(*g_rpc_node, coins);
 
     // Parse the prevtxs array
     ParsePrevouts(request.params[2], &keystore, coins);
@@ -890,6 +891,7 @@ static UniValue testmempoolaccept(const JSONRPCRequest& request)
         max_raw_tx_fee_rate = CFeeRate(AmountFromValue(request.params[1]));
     }
 
+    CTxMemPool& mempool = EnsureMemPool();
     int64_t virtual_size = GetVirtualTransactionSize(*tx);
     CAmount max_raw_tx_fee = max_raw_tx_fee_rate.GetFee(virtual_size);
 
@@ -1508,6 +1510,7 @@ UniValue utxoupdatepsbt(const JSONRPCRequest& request)
     CCoinsView viewDummy;
     CCoinsViewCache view(&viewDummy);
     {
+        const CTxMemPool& mempool = EnsureMemPool();
         LOCK2(cs_main, mempool.cs);
         CCoinsViewCache &viewChain = ::ChainstateActive().CoinsTip();
         CCoinsViewMemPool viewMempool(&viewChain, mempool);