Cleanup various obsolete build issues

[DennisHeimbigner]

Description

Remove various obsolete build options. Also do some code movement.

Specific Changes

• The remotetest server is sometimes unstable, so provide a mechanism to force disabling calls to remotetest.unidata.ucar.edu. This is enabled by adding a repository variable named REMOTETESTDOWN with the value "yes".
• Fix CMakeLists.txt to use the uname command as an alternate to using the hostname command (which does not work under cygwin).
• Remove the JNA stuff as obsolete
• Remove the ENABLE_CLIENTSIDE_FILTERS options since it has been disabled for a while.
• Fix bad option flag in some github action .yml files: change --disable-xml2 to --disable-libxml2
• Collect globalstate definitions into nc4internal.h
• Remove ENABLE_NCZARR_FILTERS_TESTING option as obsolete and replace with ENABLE_NCZARR_FILTERS
• Move some dispatcher independent functions from libsrc4/nc4internal.c to libdispatch/ddispatch.c
• As a long term goal, and because it is now the case that --enable-nczarr => USE_NETCDF4, make the external options --enable-netcdf-4 and --enable-netcdf4 obsolete in favor of --enable-hdf5 We will do the following for one more release cycle. 1. Make --enable-netcdf-4 be an alias for --enable-netcdf4. 2. Make --enable-netcdf4 an alias for --enable-hdf5. 3. Internally, convert most uses of USE_NETCDF_4 ad USE_NETCDF4 to USE_HDF5 After the next release, --enable-netcdf-4 and --enable-netcdf4 will be removed.