Better unicode character display-width calculation (in columns)

Tested with Windows Terminal Version: 1.18.10301.0 and all codepoints between
0x100 and 0x1FFFF, this change reduces the width mismatches from > 8000 to
349. The "Zero width" mismatches are probably the most important/glaring and
will need to be addressed next (since some terminals don't move the cursor
for zero width chars, and some do).