Adds two commands (globalNextSearchEntry, globalPreviousSearchEntry)
implemented by GlobalNextPrevSearchEntryHandler. The handler invokes
gotoNextMatch() / gotoPreviousMatch() on the active
AbstractTextSearchViewPage.

Key bindings:

ALT+. — next search result

ALT+, — previous search result

CMD+OPT+. / CMD+OPT+, — macOS alternatives

Allows navigating search results without leaving the editor.

Fixes: https://github.com/eclipse-platform/eclipse.platform.ui/issues/3240