fix debug console to handle more than one graphics mode in a single escape sequence

[dyc3]

According to ascii-table.com, the spec allows for more than one graphics mode to be specified at a time.

[msftclas]

All CLA requirements met.

[isidorn]

@dyc3 thanks a lot for your contribution! This looks great to me.
However do you have an example where this contribution clearly helps?
Also does this maybe fix one of #21423 #6845

[dyc3]

Sure, @isidorn.
Here's before my fix:

and after:

This would appear to fix #6845, but not #21423. I think that how the function is currently written does not make #21423 easy to fix, and it'll probably have to be rewritten for that.

[isidorn]

@dyc3 I checked and this indeed fixes #6845 - great!
In the after picture I do not see the actual difference since it is cutoff but does not really matter.
The only thing which makes me nervous is the while (chr !== 'm') loop which can spin infinetely. Can we rewrite this in such a way that we are sure it will always finishes?

[dyc3]

@isidorn Ah, I didn't see that before. I'll see what I can figure out.

[dyc3]

Unless there is something I'm missing, there is a practical limit to the number of graphic modes specified at one time: bold, underscore, blink, reverse video, concealed, foreground color. and background color. So limiting codes to a length of 7 at most should do the trick.

[isidorn]

@dyc3 looks good, thanks a lot. Merging it in