Unified HMI: Add distributed display framework

Unified HMI: Add distributed display framework

Add the distributed display framework to control the layouts of the
apps remotely rendered with remote-virtio-gpu (RVGPU).
As meta-distributed-display-fw is added to meta-uhmi, change feature
name from agl-rvgpu to agl-uhmi.

Details of the contents of meta-distributed-display-fw
- ucl-tools: unified clustering tools, launch applications for multiple
platforms and manage execution order and survival.
- ula-tools: unified layout tools, application layout for virtual
displays on virtual screen (mapped from physical displays).

Bug-AGL: SPEC-5254

Change-Id: I9dbe693534cf513ebf9f4b5b43728c67243f3d8b
Signed-off-by: Kenta <murakami.kenta002@jp.panasonic.com>