Enable signet chain configs

This enables adding of signet chain configs in bitcoin.conf.
This enables running of multiple signets with diffrent configurations

i.e
chain=signet_xxxx

[signet_xxxx]
seednodes=x.x.x.x
signetchallenge=xxxxxxxxx

src/chainparams.cpp

@@ -43,6 +43,20 @@ void ReadSigNetArgs(const ArgsManager& args, CChainParams::SigNetOptions& option
     }
 }
 
+void ReadSigNetChainArgs(const ArgsManager& args, CChainParams::SigNetOptions& options) {
+    const auto chain = args.GetArg("-chain", "");
+    if (chain.starts_with("signet_")){
+        auto seed_node = args.GetSectionArg(chain, "signetseednode");
+        if (!seed_node.empty()) {
+            options.seeds.emplace(seed_node);
+        }
+        auto signet_challenge = args.GetSectionArg(chain, "signetchallenge");
+        if (!signet_challenge.empty()) {
+            options.challenge.emplace(validateSignetChallenge(signet_challenge));
+        }
+    }
+}
+
 void ReadRegTestArgs(const ArgsManager& args, CChainParams::RegTestOptions& options)
 {
     if (auto value = args.GetBoolArg("-fastprune")) options.fastprune = *value;
@@ -120,6 +134,7 @@ std::unique_ptr<const CChainParams> CreateChainParams(const ArgsManager& args, c
     case ChainType::SIGNET: {
         auto opts = CChainParams::SigNetOptions{};
         ReadSigNetArgs(args, opts);
+        ReadSigNetChainArgs(gArgs, opts);
         return CChainParams::SigNet(opts);
     }
     case ChainType::REGTEST: {

src/common/args.cpp

@@ -388,6 +388,21 @@ std::vector<std::string> ArgsManager::GetArgs(const std::string& strArg) const
     return result;
 }
 
+std::vector<std::string> ArgsManager::GetSectionArg(const std::string& section, const std::string& strArg) const
+{
+    std::vector<std::string> result;
+    LOCK(cs_args);
+    if (auto* _section = common::FindKey(m_settings.ro_config, section)) {
+        if (auto* values = common::FindKey(*_section, strArg)) {
+            for (int i = 0; i < values->size(); i++) {
+                result.push_back((*values)[i].get_str());
+            }
+
+        }
+    }
+    return result;
+}
+
 bool ArgsManager::IsArgSet(const std::string& strArg) const
 {
     return !GetSetting(strArg).isNull();

src/common/args.h

@@ -252,6 +252,15 @@ class ArgsManager
      */
     std::vector<std::string> GetArgs(const std::string& strArg) const;
 
+    /**
+     * Retrieves values associated with a specified argument in a given configuration section.
+     *
+     * @param section section in m_settings.ro_config to seach
+     * @param strArg Argument to get (e.g. "-foo")
+     * @return Vector of string values for the argument in the configuration file.
+     */
+    std::vector<std::string> GetSectionArg(const std::string& section, const std::string& strArg) const;
+
     /**
      * Return true if the given argument has been manually set
      *

src/util/chaintype.cpp

@@ -29,7 +29,7 @@ std::optional<ChainType> ChainTypeFromString(std::string_view chain)
         return ChainType::MAIN;
     } else if (chain == "test") {
         return ChainType::TESTNET;
-    } else if (chain == "signet") {
+    } else if (chain == "signet" || chain.starts_with("signet_") ) {
         return ChainType::SIGNET;
     } else if (chain == "regtest") {
         return ChainType::REGTEST;