fix: Always tell Flame API which modloader we are using

Fixes #206 partially. Although we don't list mods that have no
compatibility with the mod loader we are using, mods that have support
for both loaders still show up, and the versions for both the loaders
are still shown.

Also simplifies a little the logic in
FlameModIndex::loadIndexedPackVersions

launcher/ui/pages/modplatform/flame/FlameModModel.cpp

@@ -175,13 +175,13 @@ void ListModel::performPaginatedSearch()
         "pageSize=25&"
         "searchFilter=%2&"
         "sort=%3&"
-        "%4"
+        "modLoaderType=%4&"
         "gameVersion=%5"
     )
         .arg(nextSearchOffset)
         .arg(currentSearchTerm)
         .arg(sorts[currentSort])
-        .arg(hasFabric ? "modLoaderType=4&" : "")
+        .arg(hasFabric ? 4 : 1) // Enum: https://docs.curseforge.com/?http#tocS_ModLoaderType
         .arg(mcVersion);
 
     netJob->addNetAction(Net::Download::makeByteArray(QUrl(searchUrl), &response));