GitLab

Use simpler icons.
paint-none will have to be replaced in the future, but we do not have
any similar icons with better names now.

it stays there just for input area

use the c++ part aain for hasCloseableActiveWindow

errors--

use the kwin effect now, use proper api
and never minimize any window

* no more randomly minimizing windows
* use showdesktop effect
* use directly kwayland for show desktop

almost entirely port the task switcher to the new
libtaskmanager. still needs porting
for the single close current window button

close should always close now

peek fixed
unintended task activation shouldn't happen anymore

keep all windows minimized except the active one and minimize everything
when the task manager is open

FIXME

the panel still looks the same

As a nice side-effect this allows us to enable/disable the close button
depending on whether we have a window to close.

Introduces new dependency on KWayland and uses it to try to resolve the
PlasmaWindowManagement interface. If available that's used to trigger
showing desktop state.