Support for choosing different kernels on aarch64

[You-never-know]

This new feature allows users to choose the kernel option on aarch64. It is needed for automatic tests.

[You-never-know]

As this introduces a new option for anabot recipes, the documentation will need to be updated as well either once the PR #40 closes, or as a part of it.

[You-never-know]

@jikortus @jstodola I believe, you are the best people to review these changes once you have time for it. :)

[jikortus]

Dane, thank you for implementing the new functionality! It looks fine, I'd only suggest to improve the action results handling a bit.

[You-never-know]

Link to beaker jobs testing this functionality are in Jira :) RTT-5270

[jikortus]

@You-never-know Dane, thank you for the fixes and sorry for the delay. Please have a look at NotFoundResult handling (other than that there are a few more suggestions for improvement, though not critical).

[jikortus]

BTW, I forgot one thing - please document the changes in recipe elements documentation.

[You-never-know]

@jikortus Thank you for the review and suggestions, I will look into them and improve the code.

[jikortus]

Dane, thank you for implementing my suggestions. I have an idea about how you might fix the translation (not sure, just an idea), you could give it a try if it doesn't take too much time. Other than that there are a few small details, overall I like how the code looks like :-).

[jikortus]

@You-never-know Awesome, I'm glad you were successful in fighting the translation issue :-). Thank you for the code!