[eclipse-pmc] API Change: Menu Contribution support for activities

[Paul Webster <Paul_Webster@xxxxxxxxxx>]

As part of the Menu Contribution plan item (bug 154130) I need to request
an API re-ordering to allow activities to be applied to user-supplied
visibleWhen and to support restrictions on visibleWhen evaluation.

GOALS/BENEFITS:
- ensure that client menu contributions also respect activities

CORRESPONDING BUG:
[Contributions] need a way to automatically associate visible when clauses
to user contributed items
https://bugs.eclipse.org/bugs/show_bug.cgi?id=175892

RISKS:
- Any clients that use AbstractContributionFactory directly or
IMenuService#registerVisibleWhen(*) will be broken.

PERFORMANCE IMPACTS:
- minimal (expressions will be massaged when they are registered)


--
Paul Webster