Port of moby/buildkit#6569 to buildx. Adds --memory, --memory-swap,
--cpu-shares, --cpu-period, --cpu-quota, --cpuset-cpus, and --cpuset-mems
flags to build, plus the equivalent bake target attributes and compose
x-bake fields.
Signed-off-by: Jiří Moravčík <jiri.moravcik@gmail.com>
