Draft: flutter: Add layer

This revision belong to kirkstone branch.

It has been checked on onrio kirkstone base using downstream project:

https://gitlab.eclipse.org/eclipse/oniro-blueprints/experimental/flutter/meta-oniro-blueprints-flutter/

Relate-to: #669 (closed) Forwarded: !4 (closed) Relate-to: https://rzr.github.io/rzr-presentations/docs/oniro-community/#/18 Relate-to: https://gitlab.eclipse.org/pcoval/oniro-presentations/-/wikis/ Relate-to: https://booting.oniroproject.org/distro/oniro/-/merge_requests/541 Relate-to: https://gitlab.eclipse.org/pcoval/meta-oniro-blueprint-flutter/-/wikis/ Signed-off-by: Philippe Coval philippe.coval.ext@huawei.com