Reduce complexity in ConditionalAssignment
Reduce complexity in ConditionalAssignment

* Extract `white_space_range` from `remove_whitespace_in_branches` in
  `RuboCop::Cop::Style::ConditionalCorrectorHelper`.
* Split `correct` and `move_assignment_inside_condition` into smaller
  methods in `RuboCop::Cop::Style::CaseCorrector'.

jonas054/rubocop,jonas054/rubocop