Allow reordering terminal instances

[nlisker]

Multiple terminals can be open in the Terminal view:

It's not possible to reorder them with mouse click-and-drag like it is possible to reorder views or editor tabs. I suggest adding the same functionality there.

Build id: I20260518-1800
Windows 10

[vogella]

CTabFolder does currently not allow to re-order its tabs via content. I will try to add it to SWT and once we have this, we can re-use it here.