ENH: Method to recover IntervalIndex when reloaing plain-text files

[benkrikler]

When an IntervalIndex is written to a plain-text format (csv or with to_string()) the output is well-formatted. If I now reload that CSV file, the IntervalIndex is now recreated as a series / index of strings.

A useful feature would be to convert that string index back into an IntervalIndex. This could potentially be done automatically in the read_csv and read_table methods.

I've implemented such a function into my own code and extracted it to this gist:
https://gist.github.com/benkrikler/cfa0f3703358d5bd7b5abd5fae36db29

I'd need some guidance, but I'd be happy to try turning this into a PR if it were wanted.

[jreback]

see
#23228

and associated PR (which is stale if i want to work on it)

[jreback]

cc @jschendel

[jorisvandenbossche]

I think the first step is to have a constructor for IntervalIndex from strings? (independent of integration in the csv reading)