feat: wireplumber support

Adds basic support for showing volume via wireplumber. Allows specifying
the node-id or falling back to the default Audio/Sink node id if node-id
is not set. If tooltip on hover is enabled, will show `{node_name}` by
default otherwise `tooltip-format`.

Format replacements:

`{volume}` - Volume in percentage
`{node_name}` - The node's nickname (`node.nick` property)

src/factory.cpp

@@ -137,6 +137,11 @@ waybar::AModule* waybar::Factory::makeModule(const std::string& name) const {
     if (ref == "jack") {
       return new waybar::modules::JACK(id, config_[name]);
     }
+#endif
+#ifdef HAVE_LIBWIREPLUMBER
+    if (ref == "wireplumber") {
+      return new waybar::modules::Wireplumber(id, config_[name]);
+    }
 #endif
     if (ref == "temperature") {
       return new waybar::modules::Temperature(id, config_[name]);