FindHDF5: Prefer h5hl* compilers for HDF5_FIND_HL

Prefer `h5hlcc`, `h5hlc++`, and `h5hlfc` compilers when HDF5's HL libraries
are requested. These include the `-lhdf_hl` in the command line, whereas
the non-hl compilers (like `h5cc`) do not. Using the latter, therefore,
leads to cmake complaining about not finding the `HDF5_HL` libraries even
though they are present in the same location as the `hdf5` library itself.

Fixes: #23261