[FEATURE REQUEST] Support statefully managing KV secrets

[lkubb]

Is your feature request related to a problem? Please describe.
In specific circumstances, it can be helpful to have a state that manages the contents of a KV secret path.

Describe the solution you'd like
Add a vault_secret state module with present, absent functions.

Describe alternatives you've considered
Some module.run + requisite quackery.

Additional context
Mostly exists, needs tests.