Taking a complement set operation flips the booleans on the masked area

[jeremyreffin]

Describe the bug
If you have chosen a shape extent (e.g. Wealden District Council) then the areas outside the extent should always be excluded. However the Complement set operation flips the bits in the masked out area.

To Reproduce
Steps to reproduce the behavior:

1. Choose an extent like WDC
2. Take a boolean feature from some input (e.g. coniferous woodland)
3. Apply the Complement operation
4. The result will show TRUE bits for the area outside the extent

Expected behavior
Area outside the extent should always be ignored

Screenshots
Attached

[paulthatjazz]

Attached PR should deal with the issue.

Creating a new issue to refactor the performOperation worker to incorporate the masks when we have more time to deal with tech debt. This should consider the mask within the operation instead of applying the mask after to improve efficiency.