buildx/store
Justin Chadwell ef0cbf20f4 buildx: warn on editing nodes
Previously, editing nodes to contain a new set of driver options or
config files was unsupported, and silently dropping them. In this patch,
we update with these, as well as add a new warning message that any new
options may not taken into account until the builder restarts (which
may apply to the flags, platforms and endpoints as well).

Signed-off-by: Justin Chadwell <me@jedevc.com>
..
storeutil set build-args from docker proxy configuration
nodegroup.go buildx: warn on editing nodes
nodegroup_test.go driver: allow setting driver opts
store.go Remove uses of deprecated io/ioutil
store_test.go Remove uses of deprecated io/ioutil
util.go commands: add implementations for create, use, rm, stop