bootstrap: Fix "make test" and "make package" targets (#14989)

Since commit v3.0.0-rc1~374^2 (Refactor internal resource location APIs
and initialization, 2013-11-07) a bootstrap-built "cmake" tries to
reference "ctest" and "cpack" executables next to itself, which never
exist.  Teach cmSystemTools::FindCMakeResources, when bootstrap-built,
to refer to the "ctest" and "cpack" executables in the location where
they will be built after "make".