feat(CordovaError): support for error cause & more

[raphinesse]

Motivation and Context

This allows us to properly wrap caught errors in a CordovaError:

try {
   builder.build(); // throws Error('foo not found')
} catch (err1) {
    throw new CordovaError('Build failed', err1));
}

Assume we catch above CordovaError as err2, then we can obtain some nicely formatted information from it:

console.log(err2.message);

CordovaError: Build failed: foo not found

console.log(CordovaError.fullStack(err2));

CordovaError: Build failed
    at ...
    at ...
caused by: foo not found
    at ...
    at ...

This is a follow-up to #117. Should preferably be merged after #120.

Description

This commit bases CordovaError on the popular joyent/node-verror.

We actually use @netflix/nerror, a VError fork for now. That's because
we do not want printf style error formatting support and that fork
allows to disable it. There's ongoing work to integrate that change
into the original VError.

So basically CordovaError behaves like PError but with all the static
methods from VError and different parameter ordering for its
constructor.

One change that could break some existing tests in repositories that use
cordova-common is that toString (for errors without a cause argument)
now behaves like the Error default again:

new CordovaError('foo').toString();
// old result: 'foo'
// new result: 'CordovaError: foo'

Here's an overview of available similar packages.

Testing

Added tests that exercised the parts of the VError API that we will be using.

[brody2consult]

LGTM

[codecov-io]

Codecov Report

Merging #121 into master will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #121      +/-   ##
==========================================
+ Coverage   88.02%   88.04%   +0.02%     
==========================================
  Files          20       20              
  Lines        1169     1171       +2     
==========================================
+ Hits         1029     1031       +2     
  Misses        140      140              

Impacted Files	Coverage Δ
src/CordovaError.js	100.00% <100.00%> (ø)

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[raphinesse]

FYI: My plan is to merge this after the big refactor PRs have all landed