These functions are very specific to the mode.
More modes can support snap, and there is no reason to keep all
callbacks for each mode in the transform_snap.c file.
clipping (even if the proportional edit itself is disabled)
Checking T_PROP_EDIT_ALL returns true for _any_ of the options, so just
check for T_PROP_EDIT.
Note: this might expand to other similar checks (e.g. header text)
Maniphest Tasks: T77068
Differential Revision: https://developer.blender.org/D7927
Follow up of b2ee1770d4c3 and 10c2254d412d, part of T74432.
Now the area and region naming conventions should be less confusing.
Mostly a careful batch rename but had to do few smaller fixes.
Also ran clang-format on affected files.