Enable shortcuts with buttons invisible (#1580) (#1800)

* Make `ShortcutsWidget` load all shortcuts

`ShortcutsWidget" now loads shortcuts for all capture widgets,
regardless of enabled state in 'Interface settings'.

Also removed unnecessary indirection which made the API confusing:

- Removed `ConfigHandler::setShortcutsDefault` which was only called
  once on a temporary `ConfigHandler` and hence had no effect

- Removed function `ConfigHandler::shortcuts`

- `ShortcutsWidget` now calls `ConfigShortcuts::captureShortcutsDefault`
  directly instead of through `ConfigHandler::shortcuts`

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Enable shortcuts for hidden buttons

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix crash if ButtonHandler has no buttons

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* obligatory clang-format

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

src/core/controller.cpp

@@ -64,9 +64,6 @@ Controller::Controller()
     m_appLatestVersion = QStringLiteral(APP_VERSION).replace("v", "");
     qApp->setQuitOnLastWindowClosed(false);
 
-    // set default shortcusts if not set yet
-    ConfigHandler().setShortcutsDefault();
-
     // init tray icon
 #if defined(Q_OS_LINUX) || defined(Q_OS_UNIX)
     if (!ConfigHandler().disabledTrayIconValue()) {