Intended to match the rest of the UI which is less rounded these days.
See inline comment for reason for not matching `FormControl` corner
radius just yet.
Saves having this defined in 20+ places. If we ever make any changes to
shear, it's 100% going to need to be applied to every usage (there will
never be a case of multiple different shears in the game).
Also fixes a mismatching definition in `ShearedNub`.
Rather than control the propagation of the value between the slider and
the textbox, add a property that controls the propagation of the value
between the bindables inside the form control to external bindables.
This will help alleviate issues where the external bindable update
incurs overheads due to having heavy change callbacks attached.