Add autogroups on UnitCreated

[hihoman23]

Work done

The autogroup widget adds the control groups on unit creation on immediate mode.

closes #3449

[badosu]

This is a very problematic piece of code, I am unable to review or test this properly, I just want to remark to thoroughly test the autogroup widget use cases (immediate mode on/off, built from factory with order/not, rezzed, given, captured, built in place by mobile builder (e.g. consul) etc)

[WatchTheFort]

@hihoman23 Has this been tested in line with badosu's comment?

[hihoman23]

No, I sadly haven’t gotten to it.

[badosu]

Yeah, don't mean to block others work unnecessarily.

It's just too often we see contributions in widgets with lots of features creating regressions up to a point they get unusable later and very hard to fix back to original state (e.g. mex snap, that I had to fix like 4 times over again until I simply gave up).

[badosu]

Normally I don't ask this for simple changes (even though this looks like a simple one), just widgets which feature a lot of different modes and use cases. Often one gets their own use case 'fixed' while breaking some other untested one.

One option is to ask players to playtest it (I often do and ask so, pinging and asking the testers discord group for assistance) as a custom widget and, if after a few weeks no issues are found, then at least we have some 'good enough' testing in place (this unfortunately only tests the 'popular' use cases, but it also can find a lot of smaller bugs youd never test). The other option is for the author or someone else to thoroughly go through all options and expected scenarios to make sure all is good.

This seems like something one can test on their own, the tricky part (sometimes) is knowing all expected scenarios autogroup should satisfy.

[sprunk]

Could have testing instructions in the comments, listing cases.