Support commas in tag annotation.

[lkysow]

Commas can be set by escaping with backslash. Fixes #719

Example:

annotation: "this,supports,commas\,now"

Becomes:

["this", "supports", "commas,now"]

How I've tested this PR:

• unit tests

How I expect reviewers to test this PR:

• code

Checklist:

• Tests added
• CHANGELOG entry added

  HashiCorp engineers only, community PRs should not add a changelog entry.
  Entries should use present tense (e.g. Add support for...)

[t-eckert]

Very clean! I like it!

[ndhanushkodi]

Looks good!!

[erdanzhang]

@lkysow Thanks for fixing!!
However, when I tried to add service tags into my k8s services like

template:
    metadata:
      annotations:
        consul.hashicorp.com/service-tags: mid\,dle,com\,ma

When I use curl to get the service tags, http://127.0.0.1:8500/v1/catalog/services

{
    "test-svc": [
        "dle",
        "com\\",
        "ma",
        "mid\\"
    ],
}

You can see the tag is incorrectly parsed. I suspect it may be related to the double slash \, wondering if that is a known bug/issue, can I resolve it by upgrading the version or is there some clever workaround?

Thanks for the helping, this is current the blocker for our team to onboard using Consul :)