add trends command

[majesticio]

openaq trends would require measurands_id and and locations_id so I am not sure what is the best way to implement it. Could be
openaq trends location 2178 measurand 2. Likely would only be for power users so they may be willing to put in the effort. Would also need to include optional flags for --period (month, day, year) --from and --to

[majesticio]

perhaps would be better as an optional flag for locations?
openaq locations get 2178 --trends 2 <-- 2 is the measurand ID. This seems a bit clunky

[russbiggs]

This is a tough one. I htink the most semantic way to do it would be:

openaq trends list 2178 2

i.e. require two positional args: [locationsID] then [parametersID]. The positional args can feel a little arbitrary but woudl be the most standard way of doing it.

[majesticio]

needed flags:

• --page
• --limit
• --from
• --to
• --period