Pin an operator's result beside it, with a tab per output port #9062

Feature Summary

The result panel shows one operator at a time, and only while that one operator is selected, so two results cannot be seen side by side, and an operator's second output cannot be seen at all.

Part of #9052.

Proposed Solution or Design

As settled in #8842: pinning an operator's hover preview turns it into a window beside the operator with the whole result table. Several windows can be open at once; each moves with its operator, and each can be dragged and resized. An operator with more than one output gets a tab per output in its window.

Affected Area

Workflow UI