Use get_char_size(' ') to calculate space width.

[bruvzg]

Fixes regressing form Text Server implementation (get_char_size('m') was accidentally used.)

[akien-mga]

Thanks!

[reduz]

Ah, I attempted a different fix here in #45923 which I believe is more correct. Spaces are generally inconsistent between fonts and not a good indication of size, which is why sometimes I used 'x' instead. This is specially a problem with mono-spaced fonts which, when using space, will have a huge minimum size.

This PR also does not fix the scale problem, which I fixed in mine.

[bruvzg]

Spaces are generally inconsistent between fonts and not a good indication of size, which is why sometimes I used 'x' instead.

Feel free to revert in, spaces were used before Text Server (and still used in 3.2) and change was not intentional, but they are quite inconsistent indeed.

I would use capital 'N' or 'M' (En/Em space which are standard typographic units) instead of 'm' or 'x'.

[reduz]

@bruvzg Yeah I know, this was an issue before too. I will change it to M then, thanks!

[reduz]

@bruvzg your changes for tab size are good though, so keeping those