Fix console crash and console key input

[VReaperV]

• Fixes a crash in auto-complete (start typing a command, move cursor back to start of the line, press tab)
• Fixes console key sometimes being caught in the console input sometimes. This one's a bit difficult to reproduce, I've mainly seen it happen when tabbing out before/during a map change with console open, then tabbing back in after the map loads and opening the console again. Also reproducible by setting input method to UK English in Windows 11, though it has a different underlying cause

[slipher]

I don't understand, what is the point of forming a string with words like ESCAPE, 0x63 etc.?

[slipher]

This would break the feature where you can hold ALT to type a character that would otherwise be a console key (works on some Linux environments)

[VReaperV]

Isn't that handled in SDL_EVENT_KEY_DOWN()?

[slipher]

That is where the ALT exemption is initially applied. But IIUC this new third level of console key filtering has no condition to check that, so such characters would be filtered out.

[slipher]

The way things initially go wrong is with the subtraction underflow in std::string commandText = Str::UTF32To8(GetText().substr(1, GetCursorPos() - 1));. Would be nicer to return before that

[slipher]

For future reference, the Windows 11 keyboard layout where the console key issue always happens is "United Kingdom Extended" which has a ` dead key.

There are other layouts which have an (Right)Alt + ` dead key combination; alt-tabbing in those could lead to accidentally triggering the dead key (and hence the bug) if pressing the console key while Alt is still held. I guess this never happens to me only because I always use left Alt for alt-tabbing.

Filtering out the console key itself won't get all possible cases of junk caused by dead keys. For example if a ` dead key is queued up when you open the console and then the first letter you type is e you will get è. Maybe what we would need to do is reset the text input state machine, if possible. Perhaps by turning off and on text input in SDL.