Remove `uuid` as a required column from input and result time series

[sebastian-peter]

For most time series, the time column is sufficient for uniquely addressing rows. Furthermore the combination of time and coordinate is a unique key for weather data.
Thus, we do not need (and do not want, due to its size) the redundant column uuid.

Documentation also needs to be updated accordingly, of course.

Affected input data:

• TimeSeriesEntry
  • class can probably be removed
  • affects weather data, coordinate data and "individual time series" (power, power & heat etc.)
• ResultEntity
  • can no longer extend UniqueEntity
  • affects system participant results, asset result, flex options result, thermal entity results

Examples

Apparent power time series would have the columns:
p,q,time
instead of
uuid,p,q,time

Cosmo weather before:
uuid,coordinateid,time,diffuseirradiance,directirradiance,temperature,winddirection,windvelocity
after:
coordinateid,time,diffuseirradiance,directirradiance,temperature,winddirection,windvelocity

Related discussion

• Does it make sense to get rid of the ResultEntity UUIDS? simona#415

cc @t-ober @danielfeismann fyi