Add optional provider label support

[rplevka]

Extend broker's AnsibleTower and Container provider functionality to pass labels to be set to the spawned resources.
It accepts a string of comma-separated label values.
Broker then uses awxkit session to resolve their id's (required for the job /launch payload) and eventually creates the non-existing labels.

User is required to have granted permissions for creating new labels (if that's even a thing) on AAP.

Plan is to implement the labeling functionality to all providers that have support of labels, e.g.
https://docs.docker.com/config/labels-custom-metadata/

example usage:

# ansible tower provider
$ broker execute deploy-rhel --provider-labels foo=bar,baz

translates to:

(AAP labels are single string items)

# container provider with additional labels configured in the nick:

nick:

  rhel8_docker:
    container_host: "ubi8:latest"
    environment:
      BUILD_URL: "https://intergalactic.planetary/planetary/intergalactic"
    provider_labels:
      nick_label_1: myval1
      nick_label_2: myval2


$ broker checkout --nick rhel8_docker --provider-labls cli1=val1,nick_label_2=overriden_by_cli_param
[INFO 240418 14:13:37] Using provider Container to checkout
[INFO 240418 14:13:45] Host: 97c993636de8

translates to:

$ docker inspect 97c993636de8
...
            "Labels": {
                "architecture": "x86_64",
                "broker.jenkins.url": "",
                "broker.nick_label_1": "myval1",
                "broker.nick_label_2": "myval2",
                "broker.origin": "broker_cli:rplevka",
               ...
...

[JacobCallahan]

Can you add a functional test each for tower and containers?
I think we can just skip beaker for now since I'm not sure that labels are a thing there (and it is much less commonly used).

Also, how well are these labels recovered after a sync?

[JacobCallahan]

Just a few more things. Can you also resolve the merge conflicts?