scripted-diff: Rename PACKAGE_* variables to CLIENT_*

This change ensures consistent use of the `CLIENT_` namespace everywhere
in the repository.

-BEGIN VERIFY SCRIPT-

ren() { sed -i "s/\<$1\>/$2/g" $( git grep -l "$1" ./cmake ./src :\(exclude\)./src/secp256k1 ./test ) ; }

ren PACKAGE_NAME      CLIENT_NAME
ren PACKAGE_VERSION   CLIENT_VERSION_STRING
ren PACKAGE_URL       CLIENT_URL
ren PACKAGE_BUGREPORT CLIENT_BUGREPORT

-END VERIFY SCRIPT-

src/common/settings.cpp

@@ -127,7 +127,7 @@ bool WriteSettings(const fs::path& path,
     SettingsValue out(SettingsValue::VOBJ);
     // Add auto-generated warning comment
     out.pushKV(SETTINGS_WARN_MSG_KEY, strprintf("This file is automatically generated and updated by %s. Please do not edit this file while the node "
-                                                "is running, as any changes might be ignored or overwritten.", PACKAGE_NAME));
+                                                "is running, as any changes might be ignored or overwritten.", CLIENT_NAME));
     // Push settings values
     for (const auto& value : values) {
         out.pushKVEnd(value.first, value.second);