Added Commnads to focus windows or Monitors above/below the active window (#497)

* Implement focus-window-up/down-or-monitor calls

* Fixed wrong naming of focus-window-or-monitor commands

* fix copy pase errors for focusing direction

* Fixed wrong behaviour when the current workspace is empty

* Cleanup navigation code to reduce complexity

* Fix wrong comments and add testcases for FocusWindowOrMonitorUp/Down

---------

Co-authored-by: Christian Rieger <christian.rieger@student.tugraz.at>

niri-config/src/lib.rs

@@ -949,6 +949,8 @@ pub enum Action {
     FocusColumnLast,
     FocusColumnRightOrFirst,
     FocusColumnLeftOrLast,
+    FocusWindowOrMonitorUp,
+    FocusWindowOrMonitorDown,
     FocusColumnOrMonitorLeft,
     FocusColumnOrMonitorRight,
     FocusWindowDown,
@@ -1027,6 +1029,8 @@ impl From<niri_ipc::Action> for Action {
             niri_ipc::Action::FocusColumnLast => Self::FocusColumnLast,
             niri_ipc::Action::FocusColumnRightOrFirst => Self::FocusColumnRightOrFirst,
             niri_ipc::Action::FocusColumnLeftOrLast => Self::FocusColumnLeftOrLast,
+            niri_ipc::Action::FocusWindowOrMonitorUp => Self::FocusWindowOrMonitorUp,
+            niri_ipc::Action::FocusWindowOrMonitorDown => Self::FocusWindowOrMonitorDown,
             niri_ipc::Action::FocusColumnOrMonitorLeft => Self::FocusColumnOrMonitorLeft,
             niri_ipc::Action::FocusColumnOrMonitorRight => Self::FocusColumnOrMonitorRight,
             niri_ipc::Action::FocusWindowDown => Self::FocusWindowDown,