Support custom build override of available complex items

On desktop (Ethernet connection), the ground unit pushes UDP directly, which makes the use of an actual "Link" not possible. Instead, I've moved all of Taisync support to a "manager" owned by QGCToolbox.
Added a Taisync settings with some basics already wired and running.

Allow custom builds to turn off firmware version check

Q_ENUMS is deprecated and should not be usued.
Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Custom build override for stable version check no longer needed

Stable desktop version check

Support GuidedActionsController logging

Expose root plan keys

Add new Help page under Settings

Create new, specific button for clearing mission from vehicle
Adjust sizing of DropPanel

Allow plugins to define a left placement for its custom flight widget.
When placed on the left, the action tool strip is placed on the right side.

All settings wired and persistent
Cleanup non Airmap builds

Eliminated flight widget "states"
Define flight widget top margin (plugin options)

Clarify the title of the "Video Stream" panel (instead of just "Video")

Also rename QmlPageInfo to QmlComponentInfo to cover more use cases

Also plugin'ize intrument panel PageView pages

Hide "Save Path" as it breaks the UI in General Settings.