feat: Enrich quorum listextended rpc reply (dashpay#5114)

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## What was done?
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Added the fields `numValidMembers` and `healthRatio` in `quorum
listextended` RPC reply, as we need a quick way to see the health of all
quorums with a single command.
`healthRatio` range is `[0.0 - 1.0]`
Note: The decision to include both fields was taken because we need
cover the case where a quorum was created with `minSize` members but all
of them were valid.

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doc/release-notes-5076.md

@@ -7,3 +7,5 @@ This RPC returns the following data per quorum grouped per llmqTypes:
     - `creationHeight`: Block height where its DKG started
     - `quorumIndex`: Returned only for rotated llmqTypes
     - `minedBlockHash`: Hash of the block containing the mined final commitment
+    - `numValidMembers`: The total of valid members.
+    - `healthRatio`: The ratio of healthy members to quorum size. Range [0.0 - 1.0].

src/rpc/quorums.cpp

@@ -23,6 +23,8 @@
 #include <llmq/signing_shares.h>
 #include <llmq/snapshot.h>
 
+#include <iomanip>
+
 namespace llmq {
 extern const std::string CLSIG_REQUESTID_PREFIX;
 }
@@ -100,7 +102,9 @@ static void quorum_list_extended_help(const JSONRPCRequest& request)
                         {
                             {RPCResult::Type::NUM, "creationHeight", "Block height where the DKG started."},
                             {RPCResult::Type::NUM, "quorumIndex", "Quorum index (applicable only to rotated quorums)."},
-                            {RPCResult::Type::STR_HEX, "minedBlockHash", "Blockhash where the commitment was mined."}
+                            {RPCResult::Type::STR_HEX, "minedBlockHash", "Blockhash where the commitment was mined."},
+                            {RPCResult::Type::NUM, "numValidMembers", "The total of valid members."},
+                            {RPCResult::Type::STR_AMOUNT, "healthRatio", "The ratio of healthy members to quorum size. Range [0.0 - 1.0]."}
                         }}
                     }}
                 }}
@@ -136,6 +140,11 @@ static UniValue quorum_list_extended(const JSONRPCRequest& request)
 
         auto quorums = llmq_ctx.qman->ScanQuorums(type, pblockindex, llmq_params.signingActiveQuorumCount);
         for (const auto& q : quorums) {
+            size_t num_members = q->members.size();
+            size_t num_valid_members = std::count_if(q->qc->validMembers.begin(), q->qc->validMembers.begin() + num_members, [](auto val){return val;});
+            double health_ratio = num_members > 0 ? double(num_valid_members) / double(num_members) : 0.0;
+            std::stringstream ss;
+            ss << std::fixed << std::setprecision(2) << health_ratio;
             UniValue obj(UniValue::VOBJ);
             {
                 UniValue j(UniValue::VOBJ);
@@ -144,6 +153,8 @@ static UniValue quorum_list_extended(const JSONRPCRequest& request)
                 }
                 j.pushKV("creationHeight", q->m_quorum_base_block_index->nHeight);
                 j.pushKV("minedBlockHash", q->minedBlockHash.ToString());
+                j.pushKV("numValidMembers", (int32_t)num_valid_members);
+                j.pushKV("healthRatio", ss.str());
                 obj.pushKV(q->qc->quorumHash.ToString(),j);
             }
             v.push_back(obj);