[FEATURE REQUEST] ethtool execution and state module functions for pause

[nicholasmhughes]

Describe the solution you'd like
The current ethtool execution and state modules do not support pause features. Would like the equivalent of the -a and -A parameters to ethtool.

Describe alternatives you've considered
cmd.run...

Additional context
The ethtool Python module (https://pypi.org/project/ethtool/) on which the current functionality is based does not support pause features either... and it's deprecated. The project is recommended migration to netifaces (https://pypi.org/project/netifaces/), but that module lost its primary maintainer and the GitHub repo has been archived. Building functionality around ethtool binary returns might be prudent. Grabbing the parser code from insights-core is an easy way to interpret the results as a dict.

Please Note
If this feature request would be considered a substantial change or addition, this should go through a SEP process here https://github.com/saltstack/salt-enhancement-proposals, instead of a feature request.