Stage before Desire makes more sense
Implement desire request for Docker protocol

[#75217152]
Make most of handler private

[#75217152]

Signed-off-by: Peter Parente <pparent@us.ibm.com>
Log warn and error instead of info

- warn for the case where a user may have deleted the app, unlikely the operator needs to intervene
- error for the case where the staging task id is invalid, this is a true error condition where the operator needs to step in
- [#75217152]

Signed-off-by: Peter Parente <pparent@us.ibm.com>