feat: Adding SDK support for deployment labels

[jianshen92]

What does this PR address?

python

import bentoml

bentoml.deployment.create(config_dict={..., "labels": [{"key": "hey", "value":"yo"}]})
bentoml.deployment.update(config_dict={..., "labels": [{"key": "hey", "value":"yo"}]})

bentoml.deployment.list(.., q="label:hey=yo")
# syntatic sugar for the above
bentoml.deployment.list(.., labels=[{"key": "hey", "value":"yo"}])

CLI

supports the following for bentoml deploy -f deploy.yaml

labels:
  - key: hey
    value: yo
  - key: xx
     value: yy

bentoml deployment list --label key1=value1 --label key2=value2

Fixes #(issue)

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