feat: add metadata get/delete via mod id

This is, in many cases, more reliable than name comparisons, so it's
useful specially in cases where a mod changes name between versions

Signed-off-by: flow <flowlnlnln@gmail.com>

launcher/minecraft/mod/tasks/LocalModUpdateTask.cpp

@@ -44,7 +44,7 @@ void LocalModUpdateTask::executeTask()
 {
     setStatus(tr("Updating index for mod:\n%1").arg(m_mod.name));
 
-    auto old_metadata = Metadata::get(m_index_dir, m_mod.name);
+    auto old_metadata = Metadata::get(m_index_dir, m_mod.addonId);
     if (old_metadata.isValid()) {
         emit hasOldMod(old_metadata.name, old_metadata.filename);
     }