support multi-platform build

[justadogistaken]

Describe what this PR does / why we need it

Does this pull request fix one issue?

Describe how you did it

Describe how to verify it

Special notes for reviews

[justadogistaken]

For multi-platform image, it's actually a manifest list.
It's still needs to be handled.
But the multi-platform build had been supported.
You'd better check how buildah support manifest push remove.

[codecov-commenter]

Codecov Report

Base: 21.65% // Head: 21.65% // No change to project coverage 👍

Coverage data is based on head (9e368e6) compared to base (d744765).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1820   +/-   ##
=======================================
  Coverage   21.65%   21.65%           
=======================================
  Files          72       72           
  Lines        6586     6586           
=======================================
  Hits         1426     1426           
  Misses       4974     4974           
  Partials      186      186           

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[starnop]

@justadogistaken cloud you please rebase the commits for this PR

[kakaZhou719]

@justadogistaken cloud you please rebase the commits for this PR

@starnop ,let me do it， some rebase commits was pushed by me.

[kakaZhou719]

for manifest object:
sealer manifest create localhost/my-manifest
sealer manifest add localhost/my-manifest localhost/ack-distro-amd64:v1
sealer manifest inspect localhost/my-manifest
sealer manifest push localhost/my-manifest
sealer manifest remove localhost/my-manifest sha256:be14feecd1103bdb28db7f7d09ad3ee56f7afc0bb4ddf5f0284e9dc0158e9a49
sealer manifest delete localhost/my-manifest

for mutil-arch image:
sealer build -f Kubefile -t docker.io/sealer/my-kubernetes:1.19.8 --platform linux/amd64,linux/arm64
sealer push docker.io/sealer/my-kubernetes:1.19.8 --all: push all platform image
sealer push docker.io/sealer/my-kubernetes:1.19.8: push default platform image
sealer pull docker.io/sealer/my-kubernetes:1.19.8 --platform linux/arm64

for single-arch image:
sealer build -f Kubefile -t my-kubernetes:1.19.8
sealer push my-kubernetes:1.19.8
sealer pull docker.io/sealer/my-kubernetes:1.19.8