Deprecation of image tag vs tags in controller EE definition

[j-random-geek]

What does this PR do?

With the deprecation of tag in the EE definition, anybody using only tags will find that the controller EE definition doesn't have a tag specified. This PR arbitrarily chooses the first tag in the tags list to push to the Controller EE definition. The tags list will take precedence over tag if both are defined.

It also fixes one ansible-lint complaint, that of a long line in the Pull base image task in roles/ee_builder/tasks/00_build_ee.yml.

Finally, the README was updated to incorporate the tag vs tags update, and also to list ee_aap_version as type float rather than str, as anybody formatting it as a string (i.e. in quotes) will get an error of a type mismatch on comparison of the string (AnsibleUnicode) to a float, at least with recent versions of ansible-core.

How should this be tested?

Create two definitions: one using the (deprecated) tag and the other using the new tags list. Build both and push both to Controller by calling infra.ee_utilities.ee_builder and then infra.aap_configuration.controller_execution_environments in the same play. Both images should appear with the tag specified in Controller.

Previously, an image built using tags would not have a tag specified in the Controller EE definition.

Is there a relevant Issue open for this?

Yes

Other Relevant info, PRs, etc

This is just a suggestion, and I've arbitrarily chosen the first item in the tags list as the tag to use in Controller. Please feel free to discard this and create a better solution. I'm not the best at this :)