[WIP] Implement Transit engine (#302)

[alexandernst]

This is still a WIP. Implements #302

[alexandernst]

@jeffwecan I see that there are some transit-related methods in api.v1.__init__, at lines 2267-2699.
What are those? Should I delete them?

[alexandernst]

@jeffwecan The code per-se (no unit tests atm) should be ready. Can you check it and verify if everything is ok?

[jeffwecan]

Sure, I'll scope it out as I have some more time. I'm also fine with skipping unit tests provided the integration tests cover the code reasonably enough. For the original Client class methods, you can mark them deprecated with a decorator like so: https://github.com/hvac/hvac/blob/master/hvac/v1/__init__.py#L2691-L2696

That way folks have a chance to update their usage before we drop those method entirely.

[alexandernst]

@jeffwecan Do I deprecate them starting from 0.7?

[jeffwecan]

Since these additions are intended to go out in 0.7.0, you can mark the old methods with a to_be_removed_in_version of 0.9.0 (ref: https://github.com/hvac/hvac/blob/master/CONTRIBUTING.md#backwards-compatibility-breaking-changes)

[alexandernst]

@jeffwecan 👍 Deprecated methods. Ping me if this PR needs more love!

[alexandernst]

Oh, I just saw the CI errors. Do you want me to remove the tests? @jeffwecan

[jeffwecan]

Sure! That makes sense to me.

[codecov-io]

Codecov Report

Merging #303 into master will increase coverage by 0.33%.
The diff coverage is 94.3%.

@@            Coverage Diff             @@
##           master     #303      +/-   ##
==========================================
+ Coverage   90.31%   90.64%   +0.33%     
==========================================
  Files          37       39       +2     
  Lines        1735     1893     +158     
==========================================
+ Hits         1567     1716     +149     
- Misses        168      177       +9

Impacted Files	Coverage Δ
hvac/api/secrets_engines/__init__.py	100% <100%> (ø)	⬆️
hvac/v1/__init__.py	86.01% <100%> (+0.34%)	⬆️
hvac/constants/transit.py	100% <100%> (ø)
hvac/api/secrets_engines/transit.py	93.23% <93.23%> (ø)

[alexandernst]

@jeffwecan Everything is green now! 👍 ✅

[jeffwecan]

Thanks @alexandernst! I am about to add in some changes that refactor how auth, secrets, and system backend classes are organized. Once I get those sorted I'll look to merge this in. Should be over the next day or two.

[jeffwecan]

In the meantime, do you mind if I push some changes accommodating that refractor to your branch as needed?

[alexandernst]

@jeffwecan Sure, feel free to add whatever you need 👍 😄

[alexandernst]

\o/