Fix right/bottom edge jump issue when adjust rect

Summary:
right/bottom edge move unexpected when adjust left/top edge.
To fix this issue, just set x/y before width/height

Test Plan:
    1. select a rect, make sure the right/bottom edge is beside moniter edge
    2. drag the topleft, top, top right up or drage top left, left, bottom left to left quickly, the bottom/ right edge move unexpected

Reviewers: rkflx, ngraham, #spectacle

Reviewed By: rkflx, ngraham, #spectacle

Differential Revision: https://phabricator.kde.org/D11704