Add custom error display for platforms

[carstene1ns]

Implemented currently for 3DS and SDL2. Switch and Vita are possible,
however an Error report might be generated on Switch (bad, could get
send to big N) and for Vita one would need to match framebuffer format
and such when dealing with GXM for dialog display. This is not worth
currently, since we likely migrate away from vita2d library in the
future.
Go through platform teardown code. While this may not work for every
case (e.g. out of memory on Wii), this should be cleaner.

[Ghabry]

Hm good idea with this function that must be defined per port.

This approach could be also used to reduce ifdefs in all these "get path for x" cases we have 🤔

[carstene1ns]

Ideally it would be local to main() and be called with atexit(), however no idea how reliable this is for custom C libraries.

More platform abstraction is good, these paths could go through DisplayUI interface. IMO we should rename DisplayUI someday...

[Ghabry]

This is incomplete but imo worth to be added to 0.8.0

Will rebase this next week (except if c1 wants to do it himself)

[carstene1ns]

Just rebased for now. I am still not sure, how to make this better.

error.mp4

[carstene1ns]

Using atexit() now. This works at least for all dkP platforms nowadays and others do not have specific teardown code. This simplifies it a bit.
Vita should be tested maybe.

[Ghabry]

Will do a test to figure out what Wii/WiiU do when invoking this MessageBox code

[carstene1ns]

I think it is not implemented currently.
But this falls back to our generic message handler.

For wiiu we can add it natively (erreula applet).

[Ghabry]

okay. ErrEula sounds useful :). Considering I'm actively working on Wii(U) currently I will merge this and fix any upcoming problems in the other PR(s).