Add list of VM sizes to AKS UI proxy 

Add new AKS UI proxy call, which returns Virtual Machines sizes
name list for specific location

Example test HTTP call for testing

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

Add list Clusters to AKS UI proxy

Use clusterName not a selector to target a cluster

Make rke2 ETCD apis as first class API

Audit Log at Login - Check the content-type header having charset as well which is set by Dashboard UI

Add new AKS UI proxy call, which returns array of resource
group and cluster names available to import to Rancher

    Example test HTTP call for testing

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

Support passing files into machine provisioning job

Update gke-operator to latest

Correct system-agent-upgrade-image

Remove default value for `system-agent-upgrade-image` and correct environment variable in Dockerfile to properly set the v3 `system-agent-upgrade-image` setting.
Signed-off-by: Chris Kim <oats87g@gmail.com>

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

Refactor AKS UI proxy calls

Some of the arguments to rancher-machine are paths to files needed for
provisioning. These changes add support for passing these files into the
pod when necessary.

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>