The `org.eclipse.help.searchProcessor` extension point allows to modify
the help search results. This is done by calling the `postSearch(...)`
method of all implementations of
`org.eclipse.help.search.AbstractSearchProcessor` specified by this
extension point. In some cases, the search results to be modified and
the query that are passed as parameters to the `postSearch(...)` method
may not be enough. So this change adds another `postSearch(...)` method
with additional parameters like the locale and the scopes if any. The
simpler `postSearch(...)` is be kept for backward compatibility.

Additionally, if `preSearch(...)` returns a `SearchProcessorInfo` with
an empty, non-`null` query (`""`), no search will be executed, resulting
in no search results or in the search results that has been added via
`postSearch(...)`.