Consider tests migration to bazel test

[nettle]

This is Bazel solution, so we should try to utilize "dogfooding" and use bazel approaches as much as we can, and do not transform testing to python.

Scope

1. Study bazel test based solutions and approaches, e.g.:
   • https://bazel.build/rules/testing
   • py_test, sh_test
   • https://github.com/bazelbuild/rules_testing
   • How to test that Bazel my_test rule fails when it should?
   • Bazel rules to test Bazel rules
2. Consider bazel test based approaches for unit testing and FOSS testing
   • Also consider removing python-based approaches
3. Select bazel test based approaches
4. Make decision
5. Develop a plan

Definition of Done

1. Bazel test based approach is selected
2. Decision is made
3. Migration plan is developed