Changing active side was introduced in {rB7ff6bfd1e0af} but was never
working for tools/operators other than the sculpt line mask tool.
While for most tools/operators this actually does not make sense, the
bisect tool/operator can actually benefit from it.
thx @campbellbarton for additional input!
Maniphest Tasks: T91320
Differential Revision: https://developer.blender.org/D12473