…utput

Refs openhab/openhab-core#4392.
Closes openhab#2817.

This adds a new section "Actions" to the Thing tab of the Thing page,
which provides a button for each UI-supported Thing action.
Clicking on that button will open a popup,
where action input can be configured and action output can be viewed.

Currently, action output is displayed pretty for the `result`, `qrPairingCode` and `manualPairingCode` keys of the response object.
In addition to that, the raw output can be viewed.

Signed-off-by: Florian Hotze <dev@florianhotze.com>

Signed-off-by: Florian Hotze <dev@florianhotze.com>

Signed-off-by: Florian Hotze <dev@florianhotze.com>