The IFindReplaceUIAccess currently provides access to the
IFindReplaceTarget, to which the UI is attached. The implementations for
the dialog and overlay employ reflection to access the target within the
UI implementation. It is, however, not necessary to access this
information via the find/replace UI since the tests set up the target
anyway and thus have access to it.

This change removes the according methods from the IFindReplaceUIAccess
and the reflective access from its implementations.