Types sidebar needs an option to "Create structure member at offset"

[plafosse]

When defining a type inside a large structure somewhere it would be much easier specify the offset if its known rather than scrolling to a particular offset.

It should show up in the right click menu here:

The action should just pop up a dialog with two fields:

Offset:
Type:

[fuzyll]

I implemented this while I was working on #6623. It was merged today and should be available in builds >= 5.4.9560.