Bump rancher-system-agent to v0.0.1-alpha21

Refactor AKS UI proxy calls

Signed-off-by: Chris Kim <oats87g@gmail.com>

Add norman cluster links to steve mgmt cluster object

AKS Kontainer Engine v2 will use cloud credentials. For checking AKS
cluster capabilities cloud credentials should be also used.
AKS Kontainer Engine v1 should works as before.

Example test HTTP call for testing cloud credentials

    ```
    $ curl -u $TOKEN "https://localhost:8443/meta/aksVersions?cloudCredentialId=cattle-global-data:cc-abcde&tenantId=3572c671-f13a-4d01-aa5e-b100b54111fa&region=eastus
    ```

Add tenatdId to AKSv2 cloud credentials

Bump rancher-machine version to v0.15.0-rancher60

Mutually assured destruction of v1 and v3.Cluster

vendor update rke

Bump the rancher-system-agent to v0.0.1-alpha20

Set X-API-Cattle-Auth to true/false/none

use docker client with api version negotiation

Images txt should not source blank image strings

Signed-off-by: Chris Kim <oats87g@gmail.com>

Only log errors for etcdbackup controller

true is authentication, false is unauthenticated and none is no auth

update rancher/machine to v0.15.0-rancher59

Add ui-brand and make ui-brand, ui-banners public

Various

Rename multiclusterchart to managedchart

 Allow unauthed users to access ui-pl and first-login