Update CMake to build under library

[mattjala]

Depends on the changes to CMakeVOL.cmake from HDFGroup/hdf5#3450

• REST VOL must now be built at library build time with CMake, as described in the README
• Removed build scripts, autotools files, and PREBUILT_HDF5_DIR options.
• Removed hdf5 and vol-tests submodules (recent additions and outstanding PRs to vol-tests will need to get merged to HDF5's API tests).
• CI workflow now uses ctest to run the test_rest_vol file with valgrind.
• README describes updated build process

[jhendersonHDF]

We should avoid any of the steps in this workflow file using valgrind to run tests since for the most part that will just make them take significantly longer. We can setup another workflow in the future that uses sanitizers to check for this stuff without affecting the runtime much.