refactor(RD): decouple ResourceModels from ResourcePages

This makes it so that we don't need a reference to the parent page in
the model. It will be useful once we change the page from a widget-based
one to a QML page.

It also makes tasks be created in the dialog instead of the page, so
that the dialog can also have the necessary information to mark versions
as selected / deselected easily. It also makes the task pointers into
smart pointers.

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

launcher/modplatform/modrinth/ModrinthPackIndex.h

@@ -29,7 +29,7 @@ void loadExtraPackData(ModPlatform::IndexedPack& m, QJsonObject& obj);
 void loadIndexedPackVersions(ModPlatform::IndexedPack& pack,
                              QJsonArray& arr,
                              const shared_qobject_ptr<QNetworkAccessManager>& network,
-                             BaseInstance* inst);
+                             const BaseInstance* inst);
 auto loadIndexedPackVersion(QJsonObject& obj, QString hash_type = "sha512", QString filename_prefer = "") -> ModPlatform::IndexedVersion;
 
 }  // namespace Modrinth