Add support for tags

[tzarski0]

Tags are essential for configuring dual device configuration groups. The ask is to add support for tag creation/deletion (/v1/tags API) and association/dissociation (/v1/tags/associate API) staring 20.12.

[reismarcelo]

We added support to tag-based association back in 20.9. Then in 20.12 there were a lot of changes made to it and our original code didn't work anymore. We'll work on it.