This package contains the search functions from Ada.Strings.Wide_Fixed.
They are separated out because they are shared by Ada.Strings.Wide_Bounded
and Ada.Strings.Wide_Unbounded, and we don't want to drag other irrelevant
stuff from Ada.Strings.Wide_Fixed when using the other two packages. We
make this a private package, since user programs should access these
subprograms via one of the standard string packages.