Add option to allow inexact matches in the Call Hierarchy view

While working on call hierarchy bugs, see https://bugs.eclipse.org/bugs/show_bug.cgi?id=575022, we observed multiple cases where the Call Hierarchy view would be empty but searching for references would produce potential matches.

Very often, the potential matches should have been exact matches (i.e. the empty call hierarchy was a bug). But its odd to see search results and empty call hierarchy, the Search view and Call Hierarchy view look inconsistent - the Call Hierarchy view looks to the user like it has a bug while the Search view does not (even though both have one). See e.g. the bug from https://bugs.eclipse.org/bugs/show_bug.cgi?id=549003 / https://github.com/eclipse-jdt/eclipse.jdt.core/issues/723:


We should check if we can add an option to show inexact (potential) matches to the Call Hierarchy view, ideally with a label as seen in the Search view.