Improve unit / e2e coverage of seccomp filters

[dtrudg]

Type of issue

Testing

Description of issue

The unit tests and e2e/security tests currently perform limited tests of seccomp filters being applied as expected. Unit testing checks some internal translation of actions / return codes from image-spec to libseccomp, and the effect of an ActErrno rule for a parameterized fchmod filter. e2e checks an ActKill rule on mkdir.

We should expand them so that they cover a broader range of what can be represented in json profile files.