Add code comments for addon status

[franco-martin]

While working on a CoreDNS addon issue I spent some time identifying how microk8s defines if an addon is enabled or not. I'd like to add my findings to the get_status and get_available_addons functions

My suggestion for get_status is

Get status for all available_addons based on the 'check_status' value in addons.yaml file.

:param available_addons: list of available addons
:param isReady: cluster ready status

My suggestion for get_available_addons is

Get available addons from file in ${SNAP_COMMON}/addons/core/addons.yaml file.

:param arch: current architecture

[HomayoonAlimohammadi]

Hi @franco-martin,

Thanks for your investigation and suggestion! I'd welcome you to create a PR with those comments and link it against this issue. We'll add it to the review backlog.