packagegroup-agl-core-boot: add package distro-build-manifest

packagegroup-agl-core-boot: add package distro-build-manifest

the purpose of distro-build-manifest is to generate and distribute a
unique build manifest for a given AGL image.

The recipe will generate the build manifest 'platform-build-info' at
each build (no caching) and this manifest is then stored in 2 locations:
 * image: in /etc/platform-build-info
 * deploy dir

Bug-AGL: SPEC-720, SPEC-1741

Change-Id: I934acc87e13d2f6ec867684af515b89a89a89338
Signed-off-by: Stephane Desneux <stephane.desneux@iot.bzh>