Grouped/nonGrouped CSV output by default

[szabozoltan69]

Instead of
https://github.com/IFRCGo/go-api/blob/develop/per/custom_renderers.py#L9
we should make possible to use a new argument for CSV download, grouped / non-grouped, to have narrow CSV output.

A solution might be via:

import pandas as pd
data = [
    {'a': 'value1', 'b': 'value2', 'c': ['c1', 'c2', 'c3'], 'f': 'value4'},
    {'a': 'value5', 'b': 'value6', 'c': ['c4', 'c5'], 'f': 'value7'}
]
df = pd.DataFrame(data)
df_exploded = df.explode('c')
df_exploded = df_exploded[['a', 'b', 'c', 'f']]
df_exploded.to_csv('output.csv', index=False)

Or, the DEEP solution might be considered.

[szabozoltan69]

@samshara @batpad