Added support for "spack load" in spack schema

[Mariamajib]

• Update spack schema to add support for load
• Add implementation of emitting spack load command in https://github.com/buildtesters/buildtest/blob/devel/buildtest/builders/spack.py.
• Add example buildspec to demonstrate this example in https://github.com/buildtesters/buildtest/tree/devel/examples/spack
• Add valid and invalid example for testing with regression test see https://github.com/buildtesters/buildtest/tree/devel/buildtest/schemas/examples/spack.schema.json please put a valid and invalid example so we can test this works during regression test
• Add documentation in https://buildtest.readthedocs.io/en/devel/buildspecs/spack.html add this at bottom of file

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -0.12% ⚠️

Comparison is base (c828d11) 78.38% compared to head (b2e3eeb) 78.27%.
Report is 12 commits behind head on devel.

❗ Current head b2e3eeb differs from pull request most recent head f5ec3e6. Consider uploading reports for the commit f5ec3e6 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##            devel    #1569      +/-   ##
==========================================
- Coverage   78.38%   78.27%   -0.12%     
==========================================
  Files          57       56       -1     
  Lines        6597     6575      -22     
==========================================
- Hits         5171     5146      -25     
- Misses       1426     1429       +3     

Files Changed	Coverage Δ
buildtest/builders/spack.py	10.42% <0.00%> (-0.45%)	⬇️

... and 7 files with indirect coverage changes

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[shahzebsiddiqui]

@Mariamajib so i would like you to add the documentation.

Please add your two commands buildtest build and buildtest inspect query in this section inorder to autogenerate the two examples

buildtest/buildtest/tools/docs.py

Lines 69 to 94 in eeae018

	commands_to_run = {
	f"{build_dir}/install_specs.txt": f"buildtest build -b {SPACK_EXAMPLE_DIR}/install_specs.yml",
	f"{build_dir}/env_install.txt": f"buildtest build -b {SPACK_EXAMPLE_DIR}/env_install.yml",
	f"{build_dir}/env_create_directory.txt": f"buildtest build -b {SPACK_EXAMPLE_DIR}/env_create_directory.yml",
	f"{build_dir}/env_create_manifest.txt": f"buildtest build -b {SPACK_EXAMPLE_DIR}/env_create_manifest.yml",
	f"{build_dir}/remove_environment_example.txt": f"buildtest build -b {SPACK_EXAMPLE_DIR}/remove_environment_example.yml",
	f"{build_dir}/pre_post_cmds.txt": f"buildtest build -b {SPACK_EXAMPLE_DIR}/pre_post_cmds.yml",
	f"{build_dir}/mirror_example.txt": f"buildtest build -b {SPACK_EXAMPLE_DIR}/mirror_example.yml",
	f"{build_dir}/spack_test.txt": f"buildtest build -b {SPACK_EXAMPLE_DIR}/spack_test.yml",
	f"{build_dir}/spack_test_specs.txt": f"buildtest build -b {SPACK_EXAMPLE_DIR}/spack_test_specs.yml",
	f"{build_dir}/spack_sbatch.txt": f"buildtest build -b {SPACK_EXAMPLE_DIR}/spack_sbatch.yml",
	f"{build_dir}/e4s_testsuite_mpich.txt": f"buildtest build -b {SPACK_EXAMPLE_DIR}/e4s_testsuite_mpich.yml",
	f"{build_dir}/clone_spack.txt": f"buildtest build -b {SPACK_EXAMPLE_DIR}/clone_spack.yml",
	f"{inspect_dir}/install_specs.txt": "buildtest inspect query -o --testpath install_specs_example",
	f"{inspect_dir}/env_install.txt": "buildtest inspect query --testpath install_in_spack_env",
	f"{inspect_dir}/env_create_directory.txt": "buildtest inspect query -o --testpath spack_env_directory",
	f"{inspect_dir}/env_create_manifest.txt": "buildtest inspect query -o --testpath spack_env_create_from_manifest",
	f"{inspect_dir}/remove_environment_example.txt": "buildtest inspect query --testpath remove_environment_automatically remove_environment_explicit",
	f"{inspect_dir}/pre_post_cmds.txt": "buildtest inspect query -o --testpath run_pre_post_commands",
	f"{inspect_dir}/mirror_example.txt": "buildtest inspect query -o --testpath add_mirror add_mirror_in_spack_env",
	f"{inspect_dir}/spack_test.txt": "buildtest inspect query -o --testpath spack_test_m4",
	f"{inspect_dir}/spack_test_specs.txt": "buildtest inspect query -o --testpath spack_test_results_specs_format",
	f"{inspect_dir}/spack_sbatch.txt": "buildtest inspect query --testpath spack_sbatch_example",
	f"{inspect_dir}/clone_spack.txt": "buildtest inspect query -o --testpath clone_spack_automatically clone_spack_and_specify_root",
	f"{inspect_dir}/e4s_testsuite_mpich.txt": "buildtest inspect query -o -e --testpath mpich_e4s_testsuite",
	}

Next please get into the container the command to run is docker run -it -v $BUILDTEST_ROOT:/home/spack/buildtest ghcr.io/buildtesters/buildtest_spack:latest but you should check https://buildtest.readthedocs.io/en/devel/contributing/build_documentation.html#generating-documentation-examples-for-buildtest-tutorial

Next run buildtest tutorial-examples and then only add the two files that are relevant for the PR. This command will autogenerate the entire documentation so dont add all the files.

Once the files are generated please write the documentation