Add selection coordinates display

## Describe your suggestion
A way to know the coordinates of pos1 and pos2 of each selection to be able to be seen with a command (i know we can see the two border blocks, but if we're selecting a large area, it would be easier to just do **#sel pos n** and it would show pos1's coords and pos2's coords, or any other command name for the same function)

## Settings
Hmm, maybe add a toggle so when you shift, expand, contract, or however modify a seletion, to display the new coordinates of each pos to know what has changed

## Context
Make managing areas easier, since if you use expand, shift, or otherwise move/change an area many times, its easy to lose the exact coordinates of each border (without moving over/under the thing and check my own coordinates, let alone to build up so you reach the Y coords) so a proper way to know WHAT am i selection would be really helpful OwO

## Final checklist
- [x] I know how to properly use check boxes

- [ ] I have not used any OwO's or UwU's in this issue.