helm_release: add values_sensitive attribute and cloak values

[mcpappas]

Description

In order to provide a mechanism for accepting sensitive input to a helm_release in yaml format (as described in #546) , the values_sensitive attribute was added and its keys are cloaked in metadata.values similarly to set_sensitive (changed in #480).

The values_sensitive attribute functions just like the values attribute, just with the addition of cloaking any keys that values_sensitive creates in the metadata.values attribute.

(This is my first experience with Go, but I tried to match the style and patterns in surrounding code. I know I still need to implement acceptance tests, but figured I would get the functional bits out there for feedback.)

Acceptance tests

• [ ] Have you added an acceptance test for the functionality being added?
• [ ] Have you run the acceptance tests on this branch? (If so, please include the test log in a gist)

References

Resolves #546.

Community Note

• Please vote on this issue by adding a 👍 reaction to the original issue to help the community and maintainers prioritize this request
• If you are interested in working on this issue or have submitted a pull request, please leave a comment

[hashicorp-cla]

All committers have signed the CLA.

[mcpappas]

@dak1n1, I just realized I never got this one over the finish line. Let me know if there is anything you need me to fix/change.

[victorgetz]

Any news regarding this topic we need this feature also

[idan-gur]

Same, can this get merged?

[hilariocoelho]

Same, can this get merged?

#625 includes the same feature but with tests and documentation. I think this PR should be closed and the other one merged. @dak1n1