Add HH load area profile generator

[gplssm]

Add household electricity demand time series, mapping of demand profiles to census cells and aggregated household electricity demand time series at MV grid district level.

Newly created in tables (from the docs)

• demand.household_electricity_profiles_in_census_cells: Lists references and scaling parameters to time series data for each household in a cell by identifiers. This table is fundamental for creating subsequent data like demand profiles on MV grid level or for determining the peak load at load area level
• demand.household_electricity_profiles_hvmv_substation: Household electricity demand profiles aggregated at MV grid district level.

For the review

@ClaraBuettner please have a detailed look on the second table. And if you have time, we're interested in general feedback

@gnn Could you please have a look on #260 (comment)

TODO:

• check dataset.yml for correct paths after datasets were included into databundle
• add fixed seed for random generator
• change to global seed
• add metadata according to mail discussion with @gplssm cf. mail on 17.6.21

Fixes #256
Fixes #294
Fixes #295

[nesnoj]

We solved the invalid memory alloc request error! 🥳
It wasn't caused by to_sql() but by returning the DF to the pipeline (legacy code from dataset migration), dunno why this is a problem. (@gnn so we don't need code snippets on this anymore)

2035 ran successfully, 2050 is ongoing - will report.
@nailend Please add the random seed #351 and check the contributing guidelines if there's anything missing..

UPDATE: 2050 ran successful too

[nesnoj]

I adjusted the random stuff as follows:

• obtain the seed from global cfg / CLI param
• seed the rng only once

[nailend]

Merged into weekend-run-branch

[nesnoj]

This one has been tested a couple of times now, everything works as expected. 🎉
Thank you @gplssm and @nailend for your efforts during the last months (111 commits!), this dataset is an important part of the database and will also improve ding0's DGs!

Caution: In #428 some columns have been renamed, a fix to the present PR has been added in 1fbd656, it requires #428 to work.