Graphical stack status summaries

[phraenquex]

Hangover from #1513. Revisit after #1451

@phraenquex wrote:

Add a graphical summary of the full set of statuses of each stack and all nodes (?!) as a set of emoji strings, every time you sent a message. I'm assuming you can do this by sending unicode. Like below - note: use fixed-width font, get alignment right (be precise on spaces, like I was here), > for changed up, x for changed down. (I just made up the node names.)

**Services**:  Discourse - Graph - Access - Keycloak - Squonk
Production:  🟢  🟢  🟢 x🔴  🟡 
Staging:     🟢  🟢  🔴 x🔴  🟡 
Tibor:       🟢  🟢 >🟢 x🔴  🟡 
Boris:       🟢  🟢  🟢 x🔴  🟡 
Matej:       🔴  🔴  🔴 x🔴  🟡  

**Nodes**:  
xch-production-app-large-x1: 🟢 
xch-production-app-med-x1:  >🟢
xch-dev-app-large-y1:       x🔴 
xch-dev-app-med-y1:         x🔴 

(I see the emoji name strings are different in Slack and Github.)

@alanbchristie replied:

A great idea but the checkers are implemented using Ansible playbooks, which are extremely good at monitoring and controlling services but you have access to a limited language (written in YAML). I will investigate a) what can be done with the slack module (emojis may not be supported) and b) what can be done with the language to not only report what is wrong but what has changed. I My experience with Ansible leads me to believe that the additional effort to make this "pretty" will be high, and we would be better off writing our own module with a richer language (like Python). Also, this sort of "graphical" reporting is probably best left to prometheus and grafana (when we deploy an upgraded version of the cluster?). I think we've achieved the best "bang for buck" already and further benefits may be expensive.