Fix Mongolia parser, add thermal + battery support [Mostly complete, needs some work so if someone else wants to complete this please do]

[q--]

Issue

See #5906

Description

Fixes the Mongolia parser by correcting a renamed field in the API, determining that 'Songino' stands for battery (#5906 (comment)). It also maps tpp to thermal.

Still to be done:

• From now on, I'm assuming that tpp = thermal and any remaining production = hydro, so 'unknown' needs to have an override for oil + coal instead of oil + coal + hydro. Keep the old override for the old data though, that's not based on tpp production but on total unaccounted for production and therefore should include hydro).
• Test if it works
• Formatting

(I wrote this in the GitHub web editor hoping to give someone else a starting point for fixing this, if someone else can do the last steps that would be appreciated. May even be tagged 'help wanted'.)

Double check

• I have tested my parser changes locally with poetry run test_parser "zone_key"
• I have run pnpx prettier@2 --write . and poetry run format in the top level directory to format my changes.

[VIKTORVAV99]

Looks good from a first glance!

There is a risk that unknown can contain other types than just hydro as we don't know if all of their production modes are actually reported properly for all plants. But I think this is a reasonable assumption to make given the available data.

I can take a look at it later today and add the needed override values. Sadly other contributors can't edit existing PR, only EMaps members can.

[q--]

Thank you! A small thing I didn't think of when working on this: I could also imagine that 'dts' is just coal and not coal + oil, it might've been established at some point but I don't remember.