Add more options for temporal aggregation

[lisazeyen]

This PR should add two more options to aggregate the network temporally: (1) aggregate timeseries to representative snapshots with e.g. 25sn as sector_opts would results in taking every 25th snapshot (2) using segmentation method from tsam similar to PyPSA-Eur, except that all time-dependent data is considered (to include e.g. also the COP of heat pumps) and that the options is added to overwrite the pypsa time-series with time profiles generated by tsam. For example 60SEG in sector_opts would results in 60 representative snapshots of the original timeseries.

[lisazeyen]

I am actually pretty sure that the options to aggregate to x representative snapshots with xsn was tat some point in the code. @fneum to you have any experience with overwriting the timeseries of pypsa with the ones generated by the tsam package? I just did a quick check but they didn't seem to be very similar. Therefore, I am currently setting the option to overwrite them as False and haven't moved the option to the config. We could also remove this part if it is not helpful.

[lisazeyen]

Thanks a lot for the review @fneum !