LibGUI: Some tweaks for TextEditor's will-execute-command virtual

Renamed the virtual from "on_edit_action" to "will_execute" so it
doesn't clash with our convention for Function hook names.

Also tighten the parameter type to GUI::TextDocumentUndoCommand
since that's the only kind of command it will receive.

Userland/DevTools/HackStudio/Editor.cpp

@@ -488,7 +488,7 @@ void Editor::LanguageServerAidedAutocompleteProvider::provide_completions(Functi
         data.value().position.column());
 }
 
-void Editor::on_edit_action(const GUI::Command& command)
+void Editor::will_execute(GUI::TextDocumentUndoCommand const& command)
 {
     if (!m_language_client)
         return;

Userland/DevTools/HackStudio/Editor.h

@@ -41,8 +41,7 @@ public:
     CodeDocument& code_document();
 
     virtual void set_document(GUI::TextDocument&) override;
-
-    virtual void on_edit_action(const GUI::Command&) override;
+    virtual void will_execute(GUI::TextDocumentUndoCommand const&) override;
 
     virtual void undo() override;
     virtual void redo() override;

Userland/Libraries/LibGUI/TextEditor.h

@@ -285,12 +285,12 @@ private:
     {
         auto command = make<T>(*m_document, forward<Args>(args)...);
         command->perform_formatting(*this);
-        on_edit_action(*command);
+        will_execute(*command);
         command->execute_from(*this);
         m_document->add_to_undo_stack(move(command));
     }
 
-    virtual void on_edit_action(const Command&) { }
+    virtual void will_execute(TextDocumentUndoCommand const&) { }
 
     Type m_type { MultiLine };
     Mode m_mode { Editable };