Add CABLE package.py file

To test installing the package, run

```
spack install -U -v [email protected] %[email protected] ^[email protected]
```

for compiling the serial executable, and

```
spack install -U -v [email protected] +mpi %[email protected] ^[email protected] ^[email protected]
```

for compiling the MPI executable.

packages/cable/package.py

@@ -0,0 +1,55 @@
+# Copyright 2013-2023 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# Copyright 2022 ACCESS-NRI
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack.package import *
+
+# See https://spack.readthedocs.io/en/latest/packaging_guide.html for a guide
+# on how this file works.
+
+
+class Cable(CMakePackage):
+    """The CSIRO Atmosphere Biosphere Land Exchange (CABLE) model."""
+
+    homepage = "https://github.com/CABLE-LSM/CABLE.git"
+    git = "[email protected]:CABLE-LSM/CABLE.git"
+
+    maintainers("SeanBryan51")
+
+    variant(
+        "mpi",
+        default=False,
+        description="Build MPI executable.",
+    )
+    variant(
+        "build_type",
+        default="Release",
+        description="CMake build type",
+        values=("Debug", "Release"),
+    )
+
+    depends_on("netcdf-fortran")
+    depends_on("mpi", when="+mpi")
+
+    def cmake_args(self):
+        args = []
+        if self.spec.satisfies("+mpi"):
+            args += [
+                self.define_from_variant("CABLE_MPI", "mpi"),
+                # TODO(Sean): we should let CMake find the MPI compiler instead
+                # of specifying it explicitly. However, this requires adding
+                # find_package(MPI) to the CMakeLists.txt file. This was not
+                # done in https://github.com/CABLE-LSM/CABLE/pull/200 so that
+                # we can demonstrate binary equivalence in the executables when
+                # transitioning from a Makefile based to a CMake based build
+                # system. Once find_package(MPI) is added, this file should be
+                # updated.
+                self.define(
+                    "CMAKE_Fortran_COMPILER",
+                    self.spec["mpi"].mpifc,
+                ),
+            ]
+        return args