egui 0.26 Upgrade

[elliottslaughter]

egui 0.26 added a new text-selection mode. In the process they completely rearchitected how input is handled. Unfortunately the new architecture breaks custom widgets, like our profile viewer widget.

There is partial progress on an upgrade in the egui-0.26 branch.

Generally, all the built-in widgets work. But mouse input on the main profile widget is broken. This means, for example, that you cannot click and drag to zoom. I think selecting tasks to pop up the detailed metadata windows may also be broken.

I haven't had time to dig and understand the new architecture well enough to understand how to fix things. That's the main blocker at this point. I imagine that once I figure that out, it probably will be a straightforward fix.

CC @lightsighter for visibility.