Completion models are now updated on-demand (whenever user presses Tab)

We might want some dirty-checking here, but for now it's okay

src/widgets/helper/resizingtextedit.cpp

@@ -1,4 +1,5 @@
 #include "widgets/helper/resizingtextedit.hpp"
+#include "completionmanager.hpp"
 
 ResizingTextEdit::ResizingTextEdit()
 {
@@ -86,6 +87,10 @@ void ResizingTextEdit::keyPressEvent(QKeyEvent *event)
             return;
         }
 
+        auto *completionModel =
+            static_cast<chatterino::CompletionModel *>(this->completer->model());
+        completionModel->refresh();
+
         if (!this->nextCompletion) {
             // first selection
             this->completer->setCompletionPrefix(currentCompletionPrefix);