tidy: Fix clang-tidy issues on files changed in this PR

The checks used are roughly the same as the ones proposed in the
clang-tidy PR (except perhaps that I used modernize-* instead of listing
them individually,though I don't think this caused any readability
detriments).

In ModrinthModel.cpp and FlameModModel.cpp I ignored the
modernize-avoid-c-arrays one, mostly because making the sorts array an
std::array would most likely increase the code complexity because of the
virtual function. Aside from that, the static_cast warning from
Application.h was not dealt with, since it's not in this PR's scope.

launcher/modplatform/flame/FlameAPI.h

@@ -4,7 +4,7 @@
 
 class FlameAPI : public NetworkModAPI {
    private:
-    inline QString getModSearchURL(SearchArgs& args) const
+    inline auto getModSearchURL(SearchArgs& args) const -> QString override
     {
         return QString(
                    "https://addons-ecs.forgesvc.net/api/v2/addon/search?"
@@ -25,7 +25,7 @@ class FlameAPI : public NetworkModAPI {
             .arg(args.version);
     };
 
-    inline QString getVersionsURL(const QString& addonId) const
+    inline auto getVersionsURL(const QString& addonId) const -> QString override
     {
         return QString("https://addons-ecs.forgesvc.net/api/v2/addon/%1/files").arg(addonId);
     };