Indicate that offset/exposure was used in GLM summary

[kshedden]

Currently there is nothing in the printed summary of the model fit to inform/remind you that an offset was used when fitting the model.

[josef-pkt]

I think we might have to parameterize a bit that additional information gets added to the summary.
When I looked yesterday at LASSO, I also didn't see any specific information about the penalization in the summary.

AFAIR, fit_constrained also doesn't provide the extra information about the constraints.

[josef-pkt]

offset and exposure is easier, because it applies to all fit (or our main fit) for which summary is designed for.

I think Stata adds these to the params table without filling out the inference columns.

[josef-pkt]

https://stats.stackexchange.com/questions/644896/how-to-tell-if-an-offset-term-is-used-from-glm-model-summary-in-statsmodels

bump

[josef-pkt]

see also #9100 and #9130

[josef-pkt]

#9130 has been merged and adds attributes with the names of the extra arrays offset, ...

adding to summary should be relatively easy

discrete models are still missing the names of the attributes and adding it to the summary