Fix Foreground-to-Background color switching of vector objects

If the fg-bg color was swapped rapidly enough, the resulting shape would
often have the same color (rather than it being swapped).

The reason for this being resourceManager would send us signal to change
both fg and bg, but if the delay between them is less than
colorChangedCompressor's timeout, the latter signal would be ignored.
Which would prevent the swapping from happening. The proper solutions
seem to be to either have a compressor at the source (which there does
seem to be) or have separate channel (ie different timers) for different
resources (bg, fg and gradient in *this* case).

BUG:458913
(cherry picked from commit 2264a44b)