Add support for checking if an apt::keyring is up-to-date with checksums

[NeatNerdPrime]

#1196

• Adds checksum and checksum_value parameter to apt::keyring, this should address issue/1196 as commented here Keyring File Modification Date Incorrectly Updated #1196 (comment)
• Includes tests, all green.

Summary

Provide a detailed description of all the changes present in this pull request.

Additional Context

Add any additional context about the problem here.

• Root cause and the steps to reproduce. (If applicable)
• Thought process behind the implementation.

Related Issues (if any)

Mention any related issues or pull requests.

Checklist

• 🟢 Spec tests.
• 🟢 Acceptance tests.
• Manually verified. (For example puppet apply)

[CLAassistant]

All committers have signed the CLA.

[smortex]

That looks good but we also need to adjust the apt::source defined type so that we can pass the checksum / checksum_value there too through the key parameter.

[NeatNerdPrime]

Hello again.

I added the requested changes, but whiel doing so i stumbled upon a perhaps uncomfortable situation.

Given the changes in the source_spec.rb test: https://github.com/puppetlabs/puppetlabs-apt/pull/1199/files#diff-abe1d0bffeeb2d6d33970b8d3272b76455f72cf2541de5f85678bd76817446e4

I realize that the parameter 'key' in apt::source is misleading, since it actually refers to the (deprecated) method of managing keys with the apt::key defined resource. But at the same time it is also used for apt::keyring? That just don't feel alright to me.

It begs the question: "Should we add a parameter 'keyring' to the defined resource, being mutually exclusive to the 'key' parameter, that calls upon apt::keyring and apt::key respectively?"

This could make things more clear from a user perspective and - unless Im mistaken - should be backwards compatible.

What do you people think?