Users will have access to an additional channel group (aka version channel, upgrade channel, etc), EUS which only contains extended supported versions.    

As a user, want to be able to change channel groups for an existing cluster. This allows me to ensure that my clusters are on a version upgrade path that best fits me needs.

Acceptance Criteria

• The channel assigned to the cluster is shown on the the cluster details page.  (API cluster response body: version > channel_group). NOTE: both the visual display and the sources of the channel will change from current implementation
• If a channel is not known for a given cluster "N/A" shall be displayed.  (This mimics when version is not known)
• When displaying the channel name, the first letter shall be capitalized.  For example for "stable", "Stable" will be displayed)
• There shall be an edit icon (currently designed as a pencil) next to the channel group value.
• If a user does not have cluster edit access, this edit icon will be disabled and a user cannot change the value
• If a user does have cluster edit access, then the user clicks on the edit icon, a modal will appear allowing the user to change the channel group.
• In this edit channel group modal:
  • Only channels the user has access to (usually only Stable and EUS) will be avaialble
  • By default the current channel will be selected
  • I the current version of the cluster is not available on a given channel, that channel will be disabled as an option. 
    • Note for QE this is not possible with the current implementation, since we do not get channels through API call, but have to dig through versions and filter, map those versions on channel groups.
  • The "Save"/"Submit" button will be disabled until the user choses a different channel group
  • When the user clicks "Save"/"Submit":
    • The modal will close on a success and the channel group will update on the cluster details page
    • The modal will remain open and display the error form the back-end if the api call results in an error

Implementation notes
There isn't a new endpoint to get channels. The channels will be determined by {{/api/clusters_mgt/v1/versions }} endpoint.  There will be a need to modify the call to get versions because it currently specifics that only the stable channel is returned.   Note that the EUS channel versions may not be available ins staging when work is beginning.  The versions endpoint may need to be mocked during development.

Setting the channel is a POST call to api/clusters_mgmt/v1/clusters/<cluster_id> {{with a modified "version" section.}}