graph: add VirtualSize for inspect output

Currently inspect output just shows Size info, and that usally be
very small and even 0 which is confusing.

Fixes #8016

Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
check tag's validity before building.

When user passes an invalid tag to `docker build`
(i.e.  `docker build -t abcd:A0123456789B0123456789C0123456789 .`), check the
tag first and terminate-early so user can specify the tag again

Docker-DCO-1.1-Signed-off-by: Daniel, Dao Quang Minh <dqminh89@gmail.com> (github: dqminh)
api/server/MAINTAINERS: back from vacation

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)
Merge pull request #8282 from proppy/patch-10

api/server/MAINTAINERS: back from vacation
Merge pull request #8175 from hqhq/master

graph: add VirtualSize for inspect output
Merge pull request #8276 from dqminh/8262-validate-build-tag

Fix #8262: check tag's validity before building.
builder: Fix CMD to inject /bin/sh -c when provided with a non-json value.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)