This commit adds support for the qemu-generic-arm64 machine as a basic
qemu machine for arm SystemReady devices. It requires
meta-arm-dunfell-backports in order to function.

Signed-off-by: Eilís Ní Fhlannagáin <elizabeth.flanagan@huawei.com>

In this way, a blueprint can set a silent bootloader.

Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>

This change is in line with the project's rebranding.

The collection is also changed a bit to drop the "meta-" prefix. There
is no clear standardization on the collection name. Some use an ID, some
use ID-layer, some use meta-ID etc. We have decided to use the the layer
name without the "meta-" prefix  because this is an ID, not a layer per
se.

Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>