Add modulefile support

[harshula]

Verify that Spack recognises the modules.yaml:

$ spack config get modules
modules:
  default:
    # Where to install modules
    enable:
    - tcl
    roots:
      tcl: $spack/../release/modules
      lmod: $spack/../release/lmod
    # What type of modules to use ("tcl" and/or "lmod")

    tcl:
      hash_length: 0
      exclude_implicits: true
      include:
      - access-om2
      - mom5
      - cice5
      - libaccessom2
      - oasis3-mct
      all:
        autoload: direct

    # Default configurations if lmod is enabled
        conflict:
        - '{name}'
        environment:
          set:
            SPACK_{name}_ROOT: '{prefix}'
      projections:
        all: '{name}/{version}'
    lmod:
      all:
        autoload: direct
      hierarchy:
      - mpi
  prefix_inspections:
    ./bin:
    - PATH
    ./man:
    - MANPATH
    ./share/man:
    - MANPATH
    ./share/aclocal:
    - ACLOCAL_PATH
    ./lib/pkgconfig:
    - PKG_CONFIG_PATH
    ./lib64/pkgconfig:
    - PKG_CONFIG_PATH
    ./share/pkgconfig:
    - PKG_CONFIG_PATH
    ./:
    - CMAKE_PREFIX_PATH

  # These are configurations for the module set named "default"

Verify that Gadi's module system recognises the modulefiles:

$ spack install access-om2 ^netcdf-c@4.7.4 ^netcdf-fortran@4.5.2 ^nci-openmpi@4.0.2 %intel@19.0.5.281
$ module avail

--------- /g/data/[...]/test/release/modules/linux-rocky8-x86_64 ---------
access-om2/latest  libaccessom2/master  oasis3-mct/master  
cice5/master       mom5/master