py-sphinx-immaterial: new package (#34948)

* py-sphinx-immaterial: new package

This is a new-ish theme for Sphinx that's based on MkDocs's `immaterial` theme. More on
the theme here: https://jbms.github.io/sphinx-immaterial/, but it seems to be very clear
and readable.  We *might* consider switching to it for Spack's docs.

* Update var/spack/repos/builtin/packages/py-sphinx-immaterial/package.py

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>

* Update var/spack/repos/builtin/packages/py-sphinx-immaterial/package.py

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>

* Update var/spack/repos/builtin/packages/py-sphinx-immaterial/package.py

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>

* Update var/spack/repos/builtin/packages/py-sphinx-immaterial/package.py

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>

* add note about node.js requirements

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>

var/spack/repos/builtin/packages/py-sphinx-immaterial/package.py

@@ -0,0 +1,29 @@
+# Copyright 2013-2022 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack.package import *
+
+
+class PySphinxImmaterial(PythonPackage):
+    """An adaptation of the popular mkdocs-material theme for the Sphinx documentation tool."""
+
+    homepage = "https://github.com/jbms/sphinx-immaterial"
+    pypi = "sphinx_immaterial/sphinx_immaterial-0.11.2.tar.gz"
+
+    version("0.11.2", sha256="a1c8387ca8b4da282949e474647d06f3b2f7d12fe54e9e662b962771012bf257")
+
+    depends_on("python@3.8:", type=("build", "run"))
+    depends_on("py-setuptools@42:", type="build")
+    depends_on("py-setuptools-scm@6.3.2:", type="build")
+    depends_on("py-appdirs", type=("build", "run"))
+    depends_on("py-markupsafe", type=("build", "run"))
+    depends_on("py-pydantic", type=("build", "run"))
+    depends_on("py-requests", type=("build", "run"))
+    depends_on("py-sphinx@4:", type=("build", "run"))
+    depends_on("py-typing-extensions", type=("build", "run"))
+
+    # see https://jbms.github.io/sphinx-immaterial/#material-for-sphinx for node requirements
+    depends_on("node-js@14:", type="build")
+    depends_on("npm", type="build")