test: Add pytest option to apply custom CPU template to any microVM

[zulinx86]

Reason / Changes

Sometimes we would like to test a custom CPU template for debugging / testing purposes. The new pytest option --custom-cpu-template allows us to apply the given CPU template to any microVM in any test unless it is overwritten by a test. Since cpu_template_any yields not only CPU templates but also None, the given CPU template will be used in the None case.

Testing

If a bad CPU template is passed via the --custom-cpu-template, tests where another CPU template is not given failed, meaning the bad template is applied correctly.

$ sudo tools/devtool test -- integration_tests/functional/test_cpu_all.py -k test_all_vcpus_online --custom-cpu-template bad_cpu_template.json
// snipped
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_booted-vmlinux-5.10.225-NO_CPU_TMPL-32] FAILED [  6%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_booted-vmlinux-5.10.225-static_V1N1-32] PASSED [ 12%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_booted-vmlinux-5.10.225-custom_aarch64_with_sve_and_pac-32] PASSED [ 18%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_booted-vmlinux-5.10.225-custom_v1n1-32] PASSED [ 25%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_booted-vmlinux-6.1.102-NO_CPU_TMPL-32] FAILED [ 31%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_booted-vmlinux-6.1.102-static_V1N1-32] PASSED [ 37%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_booted-vmlinux-6.1.102-custom_aarch64_with_sve_and_pac-32] PASSED [ 43%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_booted-vmlinux-6.1.102-custom_v1n1-32] PASSED [ 50%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_restored-vmlinux-5.10.225-NO_CPU_TMPL-32] FAILED [ 56%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_restored-vmlinux-5.10.225-static_V1N1-32] PASSED [ 62%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_restored-vmlinux-5.10.225-custom_aarch64_with_sve_and_pac-32] PASSED [ 68%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_restored-vmlinux-5.10.225-custom_v1n1-32] PASSED [ 75%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_restored-vmlinux-6.1.102-NO_CPU_TMPL-32] FAILED [ 81%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_restored-vmlinux-6.1.102-static_V1N1-32] PASSED [ 87%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_restored-vmlinux-6.1.102-custom_aarch64_with_sve_and_pac-32] PASSED [ 93%]
integration_tests/functional/test_cpu_all.py::test_all_vcpus_online[uvm_restored-vmlinux-6.1.102-custom_v1n1-32] PASSED [100%]

License Acceptance

By submitting this pull request, I confirm that my contribution is made under
the terms of the Apache 2.0 license. For more information on following Developer
Certificate of Origin and signing off your commits, please check
CONTRIBUTING.md.

PR Checklist

• I have read and understand CONTRIBUTING.md.
• I have run tools/devtool checkstyle to verify that the PR passes the
  automated style checks.
• I have described what is done in these changes, why they are needed, and
  how they are solving the problem in a clear and encompassing way.
• [ ] I have updated any relevant documentation (both in code and in the docs)
  in the PR.
• [ ] I have mentioned all user-facing changes in CHANGELOG.md.
• [ ] If a specific issue led to this PR, this PR closes the issue.
• [ ] When making API changes, I have followed the
  Runbook for Firecracker API changes.
• I have tested all new and changed functionalities in unit tests and/or
  integration tests.
• [ ] I have linked an issue to every new TODO.

---

• This functionality cannot be added in rust-vmm.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.93%. Comparing base (80b4cb4) to head (991bd92).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4975   +/-   ##
=======================================
  Coverage   83.93%   83.93%           
=======================================
  Files         248      248           
  Lines       27791    27791           
=======================================
  Hits        23327    23327           
  Misses       4464     4464           

Flag	Coverage Δ
5.10-c5n.metal	84.51% <ø> (ø)
5.10-m5n.metal	84.49% <ø> (?)
5.10-m6a.metal	?
5.10-m6g.metal	80.61% <ø> (ø)
5.10-m6i.metal	84.49% <ø> (ø)
5.10-m7g.metal	80.61% <ø> (ø)
6.1-c5n.metal	84.51% <ø> (ø)
6.1-m5n.metal	84.50% <ø> (ø)
6.1-m6a.metal	83.78% <ø> (ø)
6.1-m6g.metal	80.61% <ø> (ø)
6.1-m6i.metal	84.49% <ø> (ø)
6.1-m7g.metal	80.61% <ø> (ø)

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