[eclipse-pmc] API Addition for Hyperlink Detector State Mask

[Daniel Megert <daniel_megert@xxxxxxxxxx>]

In order to allow users to configure the modifier keys per hyperlink
detector new APIs are needed:
- new attribute 'modifierKeys' in '
org.eclipse.ui.workbench.texteditor.hyperlinkDetectors' extension point
- new interface 'IHyperlinkDetectorExtension2' with 'getStateMask()' method
- new method 'getModiferKeys()' in final class '
HyperlinkDetectorDescriptor'


GOALS/BENEFITS:
- users can choose the modifier key per hyperlink detector which us needed
to resolve conflicts


CORRESPONDING BUG:
- [api][navigation] Cannot resolve conflicting hyperlinking directors
      https://bugs.eclipse.org/bugs/show_bug.cgi?id=174235


RISKS:
No known risks.


PERFORMANCE IMPACTS:
- none


Dani