Use only one find_package call for zlib.

[byrnHDF]

Addresses #5155, and related #4614 #4904

zlib system installs tend to not have CMake config files and therefore require that a plain vanilla find_package call be used. This uses the find module for zlib. For more control over what gets found, an option to use config mode of find package is added. Which allows the use of static libs and better target properties. Also native zlib-ng, which usually has config files, would be better served with the config mode.

[lrknox]

2 code suggestions - indentation and missing "be". Currently testing cmake configure commands; ok so far.

[lrknox]

Tested minimal cmake configure commands, e.g. cmake -G "Unix Makefiles" -DHDF5_ENABLE_ZLIB_SUPPORT=ON ../hdf5, on jelly, ec2-ubuntu24.04, and macmini-m1. In a spack environment and outside the spack environment on jelly and macmini-m1. In the spack environment the previous zlib build in spack is added; outside it picks up the one beneath /usr.

On Windows 11 I tested with a VCPkg installed zlib, szip(libaec), and curl and ssl for ros3. I added CMake ROOT variables for these since they were not system installs. I ran builds and tests with no errors/failures on all the machines.

[jhendersonHDF]

Approved for develop, but we should discuss whether this is needed in 1.14.6

[brtnfld]

What does this get us to put into develop? Develop is not a production branch, so why is there an urgency? We have time before the 2.0 release, so why not resolve this with other interested parties if needed? We should not add a new option for 1.14 if we are not convinced it is the correct solution. We also have the option of not fixing this in 1.14.6, as this needs a targeted long-term fix plan that can involve Kitware and other parties.

[brtnfld]

Also, nearly zero comments in the code explain the logic of this fix.

[byrnHDF]

Also, nearly zero comments in the code explain the logic of this fix.

Because it is in the issues?
But I can update it.