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/ResourceDownloadTask.h

@@ -32,6 +32,7 @@ class ResourceDownloadTask : public SequentialTask {
 public:
     explicit ResourceDownloadTask(ModPlatform::IndexedPack pack, ModPlatform::IndexedVersion version, const std::shared_ptr<ResourceFolderModel> packs, bool is_indexed = true);
     const QString& getFilename() const { return m_pack_version.fileName; }
+    const QVariant& getVersionID() const { return m_pack_version.fileId; }
 
 private:
     ModPlatform::IndexedPack m_pack;