Refactored library with generated structs and improved error handling

[lornajane]

This changes ... basically everything in the library! The main goals:

• a more sane and flexible user interface so you can configure auth and then per-product operations
• autogenerated OAS behind the scenes to ensure accuracy and improve maintainability
• clear docs, tests and examples

This prototype will cover (checkboxes for what's already available): [x] SMS [x] Numbers [x] Verify [x] JWT features [x] Number Insight [x] Voice [x] Applications

[lornajane]

Note that everything in sms/ is generated code - the idea is that we can replace this if the spec changes

[lornajane]

I just pushed some changes to the error handling in the Verify section - check the README for examples and let me know what you think? ( @superdiana thanks for the moral support on this!)

[codecov-commenter]

Codecov Report

Merging #27 into master will increase coverage by 33%. The diff coverage is 62%.

@@          Coverage Diff          @@
##           master   #27    +/-   ##
=====================================
+ Coverage      29%   62%   +33%     
=====================================
  Files          16     7     -9     
  Lines         316   460   +144     
=====================================
+ Hits           92   289   +197     
+ Misses        220   126    -94     
- Partials        4    45    +41     

Impacted Files	Coverage Δ
voice.go	47% <47%> (ø)
numbers.go	51% <51%> (ø)
sms.go	62% <62%> (-38%)	:arrow_down:
auth.go	69% <69%> (+36%)	:arrow_up:
verify.go	78% <78%> (+78%)	:arrow_up:
api_transport.go	89% <89%> (ø)
ncco.go	100% <100%> (ø)
... and 1 more

---

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[seopei]

any updates when this one will get merged and released?

[lornajane]

I don't have an ETA yet, the remaining APIs to support before release are both fairly large so I don't want to make promises. Also it has to be an all-at-once release because it's a very breaking change from the current version of the library. If you can try the branch and let us know what you think that would probably help? It's subject to minor changes however!

[seopei]

Is the verify API fully implemented and well tested? Because we are just using this one. At the moment I am not so happy with the current implementation of the error handling at the master branch.

[lornajane]

@seopei ah, the Verify API part is pretty much done so I created a tag https://github.com/nexmo-community/nexmo-go/releases/tag/v0.12.0-alpha.1 if you want to try out this version and see if it's a better fit. The error handling (and accuracy with the API structs) is a major focus of this major change.

[superdiana]

I took a look at the conflicts and no major comments on those. (y)