refactor: more net cleanup

This runs clang-tidy on some other files in launcher/net/.

This also makes use of some JSON wrappers in HttpMetaCache, instead of
using the Qt stuff directly.

Lastly, this removes useless null checks (crashes don't occur because of
this, but because of concurrent usage / free of the QByteArray pointer),
and fix a fixme in Download.h

launcher/net/Sink.h

@@ -8,14 +8,15 @@ namespace Net {
 class Sink {
    public:
     Sink() = default;
-    virtual ~Sink(){};
+    virtual ~Sink() = default;
 
    public:
-    virtual Task::State init(QNetworkRequest& request) = 0;
-    virtual Task::State write(QByteArray& data) = 0;
-    virtual Task::State abort() = 0;
-    virtual Task::State finalize(QNetworkReply& reply) = 0;
-    virtual bool hasLocalData() = 0;
+    virtual auto init(QNetworkRequest& request) -> Task::State = 0;
+    virtual auto write(QByteArray& data) -> Task::State = 0;
+    virtual auto abort() -> Task::State = 0;
+    virtual auto finalize(QNetworkReply& reply) -> Task::State = 0;
+
+    virtual auto hasLocalData() -> bool = 0;
 
     void addValidator(Validator* validator)
     {
@@ -24,7 +25,15 @@ class Sink {
         }
     }
 
-   protected: /* methods */
+   protected:
+    bool initAllValidators(QNetworkRequest& request)
+    {
+        for (auto& validator : validators) {
+            if (!validator->init(request))
+                return false;
+        }
+        return true;
+    }
     bool finalizeAllValidators(QNetworkReply& reply)
     {
         for (auto& validator : validators) {
@@ -41,14 +50,6 @@ class Sink {
         }
         return success;
     }
-    bool initAllValidators(QNetworkRequest& request)
-    {
-        for (auto& validator : validators) {
-            if (!validator->init(request))
-                return false;
-        }
-        return true;
-    }
     bool writeAllValidators(QByteArray& data)
     {
         for (auto& validator : validators) {
@@ -58,7 +59,7 @@ class Sink {
         return true;
     }
 
-   protected: /* data */
+   protected:
     std::vector<std::shared_ptr<Validator>> validators;
 };
 }  // namespace Net