Fixes various pqTransferFunctionWidget issues
pqTransferFunctionWidget still is terrible at small (and massive) ranges, but this is an improvement to avoid the flicker as reported in issues #18439 (closed), #18132 (closed), and #18467 (closed). This fixes it by manually resizing axes and recomputing plot transfers when the transfer function bounds may have changed.
Fixes #18439 (closed), #18132 (closed), and #18467 (closed).
Backport: release
Edited by Utkarsh Ayachit