convert get to traverse_dict_and_list

[mchugh19]

What does this PR do?

Replaces value.get with call to traverse_dict_and_list to support list and deeper getting
Also only copy tst files from saltmaster, rather than run cp.cache_master on each invocation

Previous Behavior

saltcheck was only able to process a single depth dict in assertion_section
cp.cache_master always run

New Behavior

saltcheck's assertion_section can now traverse dicts and lists
cp.cache_files run for all *.tst files

Tests written?

No

Commits signed with GPG?

No

[mchugh19]

Based on some feedback from the slack develop channel, this is still a work in progress.

[mchugh19]

Now saltcheck should perform a cp.cache_dir for each requested state. I'd appreciate a second opinion on this logic

@gtmanfred

[mchugh19]

It appears the included solution does not work with salt-ssh, and tst files are not copied to the minion. @garethgreenaway or @Ch3LL can you recommend a better approach?

The goal is to run salt-ssh someminion saltcheck.run_state_tests somestate and have that run properly. At the moment salt-check runs cp.cache-dir for the given states, and then walks the cache looking for associated .tst files which it then renders. This works fine for the salt and salt-call cases, but not for salt-ssh. What's a better method?

[mchugh19]

I've figured out a way to support salt-ssh. It works but it might need feedback, so I've opened it as another PR for comments there. It includes the functionality of this PR, so I'll close this one out. If the saltcheck ssh wrapper isn't suitable, this PR can be re-opened.