feat: API call to gratibot to gather metrics

[densellp]

Requested feature from @jphayes

[anthonygauthier]

@densellp @Pactionly @zjorge96 was this ever worked on? I'm looking for small features/fix to take my mind off the SWA day-to-day and this seems perfect.

I was thinking of maybe having something like a trend command for Gratibot. It could be expanded with premade queries. I.e:

#shows all trends
@gratibot trend all 

#shows specific trends
@gratibot trend fistbumps-given-overtime
@gratibot trend fistbumps-received-overtime

What do you all think?