ls: move builder/node status error msg below table

[crazy-max]

follow-up #830

as suggested in #764, display builder/node status error msg below table to avoid a messy output:

$ docker buildx ls
NAME/NODE DRIVER/ENDPOINT STATUS BUILDKIT PLATFORMS
builder * docker-container
builder0 unix:///var/run/docker.sock running b6924b0 linux/amd64, linux/arm64, linux/riscv64
mac-mini-m1 tcp://mac-mini-m1.home.com:2376 running b6924b0 linux/arm64*, linux/amd64
sifive tcp://sifive.home.com:2375 running b6924b0 linux/riscv64*
builder2 docker-container
builder20 unix:///var/run/docker.sock inactive
graviton2 docker-container
node1 ssh://ubuntu@18.216.87.142 Get "http://docker.example.com/v1.24/info": context deadline exceeded
desktop-linux protocol not available
desktop-windows protocol not available
default docker
default default running 20.10.14 linux/amd64, linux/arm64, linux/riscv64, linux/ppc64le, linux/s390x, linux/386, linux/arm/v7, linux/arm/v6

now:

$ docker buildx ls
NAME/NODE DRIVER/ENDPOINT STATUS BUILDKIT PLATFORMS
builder * docker-container
builder0 unix:///var/run/docker.sock running b6924b0 linux/amd64, linux/arm64, linux/riscv64
mac-mini-m1 tcp://mac-mini-m1.home.com:2376 running b6924b0 linux/arm64*, linux/amd64
sifive tcp://sifive.home.com:2375 running b6924b0 linux/riscv64*
builder2 docker-container
builder20 unix:///var/run/docker.sock inactive
graviton2 docker-container
node1 ssh://ubuntu@18.216.87.142 error
desktop-linux error
desktop-windows error
default docker
default default running 20.10.14 linux/amd64, linux/arm64, linux/riscv64, linux/ppc64le, linux/s390x, linux/386, linux/arm/v7, linux/arm/v6
Failed to get status for graviton2 (node1): Get "http://docker.example.com/v1.24/info": context deadline exceeded
Cannot load builder desktop-linux: protocol not available
Cannot load builder desktop-windows: protocol not available

will take a look for a progress tabwriter in a follow-up

Signed-off-by: CrazyMax crazy-max@users.noreply.github.com