To use installed Intel OneAPI and CMAKE on SPACK

In order to avoid multiple installations of Intel-OneAPI and CMAKE, we can use installed ones.
Please install Install OneAPI and CMAKE via APT and put the packages.yaml under ~/.spack/ whose contents are as follows;

 $ cat ~/.spack/packages.yaml

packages:

intel-oneapi-mkl:

buildable: false

externals:

- spec: intel-oneapi-mkl@2021.4.0

prefix: /opt/intel/oneapi/

intel-oneapi-mpi:

buildable: false

externals:

- spec: intel-oneapi-mpi@2021.4.0

prefix: /opt/intel/oneapi/

cmake:

buildable: false

externals:

- spec: cmake@3.16.3

prefix: /usr

buildable: false prevents us from installing packages via SPACK.