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/ui/pages/modplatform/modrinth/ModrinthModel.cpp

@@ -4,6 +4,7 @@
 
 namespace Modrinth {
 
+// NOLINTNEXTLINE(modernize-avoid-c-arrays)
 const char* ListModel::sorts[5]{ "relevance", "downloads", "follows", "updated", "newest" };
 
 void ListModel::loadIndexedPack(ModPlatform::IndexedPack& m, QJsonObject& obj)
@@ -16,7 +17,7 @@ void ListModel::loadIndexedPackVersions(ModPlatform::IndexedPack& m, QJsonArray&
     Modrinth::loadIndexedPackVersions(m, arr, APPLICATION->network(), m_parent->m_instance);
 }
 
-QJsonArray ListModel::documentToArray(QJsonDocument& obj) const
+auto ListModel::documentToArray(QJsonDocument& obj) const -> QJsonArray
 {
     return obj.object().value("hits").toArray();
 }