support for apple silicon linux/arm64/v8 platform // multi-arch build

[haarchri]

at the moment the footloose images not running directly on apple silicon linux/arm64/v8 platform

Issue:

footloose create  
INFO[0000] Pulling image: quay.io/footloose/centos7:latest ... 
INFO[0009] Creating machine: cluster-node0 ...          
INFO[0009] Machine cluster-node0 is already created...  
INFO[0009] Creating machine: cluster-node1 ...          
FATA[0010] failed to get container id, output did not match: [WARNING: The requested image's platform (linux/amd64) does not match the detected host platform (linux/arm64/v8) and no specific platform was requested 962fd7a638a5c16539d02a3a87c9365421aeb563f0a973d0f33e241c0426353d] 

at the moment the only option is on apple silicon linux/arm64/v8 platform to build the images directly:

git clone git@github.com:weaveworks/footloose.git
cd footloose
./make-image.sh build centos7 
docker images | grep "footloose" | grep "latest"

please release new images

[luxiaba]

After build it by myself locally, I used it to create a 3-node cluster, but it seems that no node successfully runs the sshd server, so I have to manually run ssh-keygen -t ecdsa -f /etc/ssh/ssh_host_ecdsa_key && /usr/sbin/ssh-D' inside, so that footloose ssh root@node1` works fine.

[luxiaba]

I think it's relate to docker issue.