Linkpreviewer Improvements

- Have LinkPreviewers stored in NeoChatConnection so that they don't have to be reloaded everytime the MessageContentModel is refreshed
- This means the link is never changed (it will be swiched for a new previewer with the new link)
- LinkPreviewers are stored by URL so they can be re-used by any event with the same URL

BUG: 484927  (because the offending code is ripped out)

src/neochatconnection.cpp

@@ -9,6 +9,8 @@
 #include "controller.h"
 #include "jobs/neochatchangepasswordjob.h"
 #include "jobs/neochatdeactivateaccountjob.h"
+#include "linkpreviewer.h"
+#include "neochatconfig.h"
 #include "neochatroom.h"
 #include "roommanager.h"
 #include "spacehierarchycache.h"
@@ -477,4 +479,20 @@ QString NeoChatConnection::accountDataJsonString(const QString &type) const
     return QString::fromUtf8(QJsonDocument(accountDataJson(type)).toJson());
 }
 
+LinkPreviewer *NeoChatConnection::previewerForLink(const QUrl &link)
+{
+    if (!NeoChatConfig::showLinkPreview()) {
+        return nullptr;
+    }
+
+    auto previewer = m_linkPreviewers.value(link, nullptr);
+    if (previewer != nullptr) {
+        return previewer;
+    }
+
+    previewer = new LinkPreviewer(link, this);
+    m_linkPreviewers[link] = previewer;
+    return previewer;
+}
+
 #include "moc_neochatconnection.cpp"