Make menus and placeholders display appropriate custom key combos. (#4045)

* Add initial support for finding hotkey display key sequences

* Make neededArguments work

* Implement displaying key combos in SplitHeader main menu

* Make Settings search text dynamic

* Make tab hide notice use a custom hotkeys key sequence

* Make Notebook menus use custom hotkeys key combo lookup for hiding tabs

* shut up changelog ci

* Make NotebookTab menus show custom hotkeys. SCUFFED:
this does not update dynamically!

* Scuffed: Make the show prefs button setting show the key bind

* Scuffed: Make the R9K description refer to hotkeys

* @pajlada, is something like this ok?

Co-authored-by: pajlada <rasmus.karlsson@pajlada.com>

src/controllers/hotkeys/HotkeyController.cpp

@@ -1,6 +1,7 @@
 #include "controllers/hotkeys/HotkeyController.hpp"
 
 #include "common/QLogging.hpp"
+#include "controllers/hotkeys/HotkeyCategory.hpp"
 #include "controllers/hotkeys/HotkeyModel.hpp"
 #include "singletons/Settings.hpp"
 
@@ -547,4 +548,40 @@ void HotkeyController::showHotkeyError(const std::shared_ptr<Hotkey> &hotkey,
     msgBox->exec();
 }
 
+QKeySequence HotkeyController::getDisplaySequence(
+    HotkeyCategory category, const QString &action,
+    const std::optional<std::vector<QString>> &arguments) const
+{
+    const auto &found = this->findLike(category, action, arguments);
+    if (found != nullptr)
+    {
+        return found->keySequence();
+    }
+    return {};
+}
+
+std::shared_ptr<Hotkey> HotkeyController::findLike(
+    HotkeyCategory category, const QString &action,
+    const std::optional<std::vector<QString>> &arguments) const
+{
+    for (auto other : this->hotkeys_)
+    {
+        if (other->category() == category && other->action() == action)
+        {
+            if (arguments)
+            {
+                if (other->arguments() == *arguments)
+                {
+                    return other;
+                }
+            }
+            else
+            {
+                return other;
+            }
+        }
+    }
+    return nullptr;
+}
+
 }  // namespace chatterino