Enable response wrapping of PKI secrets

[tmcolby]

Methods generate_intermediate and generate_root, if called with type='exported', expose the private key in the response. Additionally, generate_certificate also exposes the private key in the response.
This PR adds the wrap_ttl keyword argument to these methods that enables response wrapping of these calls.
https://www.vaultproject.io/docs/concepts/response-wrapping

[codecov]

Codecov Report

Merging #649 (74d55b7) into develop (7a8642e) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop     #649   +/-   ##
========================================
  Coverage    84.01%   84.01%           
========================================
  Files           61       61           
  Lines         3203     3203           
========================================
  Hits          2691     2691           
  Misses         512      512           

Impacted Files	Coverage Δ
hvac/api/secrets_engines/pki.py	100.00% <100.00%> (ø)

[tmcolby]

hi, what is the cadence for approving PR's and official releases? i want to use hvac in a large enterprise project, but i need the feature in this PR. i will need to be able to pull a release from pypi using requirements.txt to satisfy the devops folks - i dont think they will like pulling from my repo and building.
so with that said - can you tell me the likely hood of this getting approved and a realistic sense if it can make it into a release? im not asking for special attention - just trying to understand if i need to go another route. thanks for any feedback.

[jeffwecan]

@tmcolby: Sorry for the delay in getting to this PR and your query! We typically aim to create new releases more-or-less anytime PRs have been merged in. In reality, I haven't been able to make as much time for this project to hit that cadence (obviously :P). That said, I was planning on release a new version, with these changes included, over the next hour or so. 👍