Move ChainNameFromCommandLine into ArgsManager and rename to GetChainName

src/bitcoind.cpp

@@ -111,7 +111,7 @@ bool AppInit(int argc, char* argv[])
         }
         // Check for -testnet or -regtest parameter (Params() calls are only valid after this clause)
         try {
-            SelectParams(ChainNameFromCommandLine());
+            SelectParams(gArgs.GetChainName());
         } catch (const std::exception& e) {
             fprintf(stderr, "Error: %s\n", e.what());
             return false;