feat: support json style tags

[nilo19]

What type of PR is this?

/kind feature

What this PR does / why we need it:

Normally we don't support special characters such as = or , in key-value pairs. These characters will be treated as separator and will not be included in the key/value literal. To solve this problem, tagsMap is introduced, in which a JSON-style tag is acceptable.

{
  "tags": "a=b,c=d",
  "tagsMap": {"e": "f", "g=h": "i,j"}
}

tags and tagsMap will be merged, and similarly, they are case-insensitive.

Which issue(s) this PR fixes:

Fixes #887

Special notes for your reviewer:

Does this PR introduce a user-facing change?

feat: support json style tags

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[coveralls]

Coverage decreased (-0.0002%) to 80.374% when pulling 2b1aee9 on nilo19:feat/tag-map into 46f2c54 on kubernetes-sigs:master.

[nilo19]

/retest

[feiskyer]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: feiskyer, nilo19

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[feiskyer]

/retest

[nilo19]

/retest

[nilo19]

/retest