Merge Snapshot to Master Branch

[leakingtapan]

Is this a bug fix or adding new feature?
merge snapshot to master branch

What is this PR about? / Why do we need it?
Ref

• Add snapshot examples #210
• Don't wait for the snapshot to be completed #209
• Add snapshots support #131

[k8s-ci-robot]

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[k8s-ci-robot]

@leakingtapan: The following tests failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
pull-aws-ebs-csi-driver-verify	3e2563b	link	/test pull-aws-ebs-csi-driver-verify
pull-aws-ebs-csi-driver-unit	3e2563b	link	/test pull-aws-ebs-csi-driver-unit
pull-aws-ebs-csi-driver-sanity	3e2563b	link	/test pull-aws-ebs-csi-driver-sanity
pull-aws-ebs-csi-driver-integration	3e2563b	link	/test pull-aws-ebs-csi-driver-integration
pull-aws-ebs-csi-driver-e2e-single-az	3e2563b	link	/test pull-aws-ebs-csi-driver-e2e-single-az
pull-aws-ebs-csi-driver-e2e-multi-az	3e2563b	link	/test pull-aws-ebs-csi-driver-e2e-multi-az

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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