Support list of pyfixest models with multiple estimation in `mt.ETable`

[leostimpfle]

Not sure if this expected, but specifying a list of pyfixest models with multiple estimation syntax currently does not work with mt.ETable.

import pyfixest as pf
import maketables as mt
data = pf.get_data(N=1_000, seed=0, model="Feols")

# This works
fmls = ["Y ~ X1 | f1 + f2", "Y ~ X2 | f1 + f2"]
mt.ETable([pf.feols(fml=fml, data=data) for fml in fmls])

# This also works
mt.ETable(pf.feols(fml="Y ~ X1 | sw0(f1, f2)", data=data))

# This fails with TypeError: No extractor available for model type: FixestMulti from pyfixest.estimation.FixestMulti_
fmls = ["Y ~ X1 | sw0(f1, f2)", "Y ~ X2 | sw0(f1, f2)"]
mt.ETable([pf.feols(fml=fml, data=data) for fml in fmls])

[s3alfisc]

Probably should work? I'll try to take a look in the next days.

[dsliwka]

Thanks @leostimpfle: I just checked. Indeed ETable currently accepts a list of pyfixest models and a FixestMulti object but not a list of FixestMulti objects. I am implementing a fix so that a list of FixestMulti objects is flattened to a list of pyfixest models and then it should work. (fyi: @s3alfisc)