Add "separated block sextant"  support

Unicode 16 (or even earlier) also has the chars `\U0001ce51` - `\U0001ce8f`  "separated block sextant" .

While implementign these seens straightforward by copy-pasting the code for "sextant" chars - it may be  interesting to evaluate the naming and API options to get to these .

(Octants and Braille will also present the same resolution with different styles)