desktop-shell:Add three new keyboard shortcuts

Fixes:#343 & #438

Add three new keyboard shortcuts to switch between
next and previous window with arrows key left
and right respectively. mod + Shift + Tab to do
reverse of mod + Tab.

mod + Left  -> previous window
mod + Right -> next window
mod + Shift + Tab -> switch to active previous window.

Signed-off-by: Veeresh Kadasani <veeresh.kadasani@huawei.com>
5 jobs for switch_active_window_with_arrows in 2 minutes and 35 seconds (queued for 1 second)
latest
Status Name Job ID Coverage
  Container Prep
passed container_prep #8584365

00:00:17

 
  Build
passed build-docs #8584367
kvm

00:00:53

passed build-native-meson-default-options #8584366
kvm

00:02:02

passed build-native-meson-no-gl-renderer #8584368
kvm

00:01:01

 
  Pages
passed docs-and-coverage #8584369

00:00:15