PythonPackage: install packages with pip (#27798)

* Use pip to bootstrap pip

* Bootstrap wheel from source

* Update PythonPackage to install using pip

* Update several packages

* Add wheel as base class dep

* Build phase no longer exists

* Add py-poetry package, fix py-flit-core bootstrapping

* Fix isort build

* Clean up many more packages

* Remove unused import

* Fix unit tests

* Don't directly run setup.py

* Typo fix

* Remove unused imports

* Fix issues caught by CI

* Remove custom setup.py file handling

* Use PythonPackage for installing wheels

* Remove custom phases in PythonPackages

* Remove <phase>_args methods

* Remove unused import

* Fix various packages

* Try to test Python packages directly in CI

* Actually run the pipeline

* Fix more packages

* Fix mappings, fix packages

* Fix dep version

* Work around bug in concretizer

* Various concretization fixes

* Fix gitlab yaml, packages

* Fix typo in gitlab yaml

* Skip more packages that fail to concretize

* Fix? jupyter ecosystem concretization issues

* Solve Jupyter concretization issues

* Prevent duplicate entries in PYTHONPATH

* Skip fenics-dolfinx

* Build fewer Python packages

* Fix missing npm dep

* Specify image

* More package fixes

* Add backends for every from-source package

* Fix version arg

* Remove GitLab CI stuff, add py-installer package

* Remove test deps, re-add install_options

* Function declaration syntax fix

* More build fixes

* Update spack create template

* Update PythonPackage documentation

* Fix documentation build

* Fix unit tests

* Remove pip flag added only in newer pip

* flux: add explicit dependency on jsonschema

* Update packages that have been added since this was branched off of develop

* Move Python 2 deprecation to a separate PR

* py-neurolab: add build dep on py-setuptools

* Use wheels for pip/wheel

* Allow use of pre-installed pip for external Python

* pip -> python -m pip

* Use python -m pip for all packages

* Fix py-wrapt

* Add both platlib and purelib to PYTHONPATH

* py-pyyaml: setuptools is needed for all versions

* py-pyyaml: link flags aren't needed

* Appease spack audit packages

* Some build backend is required for all versions, distutils -> setuptools

* Correctly handle different setup.py filename

* Use wheels for py-tomli to avoid circular dep on py-flit-core

* Fix busco installation procedure

* Clarify things in spack create template

* Test other Python build backends

* Undo changes to busco

* Various fixes

* Don't test other backends

var/spack/repos/builtin.mock/packages/py-pip/package.py

@@ -0,0 +1,15 @@
+# Copyright 2013-2021 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 import *
+
+
+class PyPip(Package):
+    """Only needed because other mock packages use PythonPackage"""
+
+    homepage = "http://www.example.com"
+    url      = "http://www.example.com/pip-1.0.tar.gz"
+
+    version('1.0', '0123456789abcdef0123456789abcdef')