[BBPBGLIB-1173]Help setting up Allen V1 model

[WeinaJi]

Copied from https://bbpteam.epfl.ch/project/issues/projects/BBPBGLIB/issues/BBPBGLIB-1173

The request from Joseph Tharayil:

I'm trying to get the Allen V1 model to run with Neurodamus. However, there are several differences between how they format their node and edge h5 files, which I'm not sure can be overcome:

Several of the mandatory fields in the node.h5 file, such as mtype, etype, threshold_current, and holding_current, are not available for the Allen model. Does Neurodamus need the correct values of these fields in order to run the simulation, or can we just insert anything?

The node.h5 file in the Allen model mixes biophysical and point neurons. Can Neurodamus handle this, or do they need to be split into separate populations?

The model_templates in the Allen model are defined as json files instead of hoc files. Can Neurodamus handle this?

The synapses in the Allen model are biexponential, while the BBP SONATA format requires Tsodyks-Markram parameters. Is there a way to model biexponential synapses?