chore: replace instanbul w/ nyc

[erisu]

Motivation and Context

instanbul is no longer maintained and we use nyc across all other repos.

Closes #72

Description

Drop instanbul
Added nyc & configs

Testing

• npm t

Checklist

• I've run the tests to see all new and existing tests pass

[codecov-io]

Codecov Report

Merging #100 into master will decrease coverage by 1.7%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #100      +/-   ##
==========================================
- Coverage   87.98%   86.28%   -1.71%     
==========================================
  Files          19       21       +2     
  Lines        1748     1560     -188     
  Branches      358        0     -358     
==========================================
- Hits         1538     1346     -192     
- Misses        210      214       +4

Impacted Files	Coverage Δ
src/util/plist-helpers.js	78.94% <0%> (-2.45%)	⬇️
src/PluginInfo/PluginInfo.js	81.59% <0%> (-1.83%)	⬇️
src/CordovaError/CordovaError.js	86.95% <0%> (-1.51%)	⬇️
src/ConfigChanges/ConfigFile.js	87.39% <0%> (-1.18%)	⬇️
src/PluginInfo/PluginInfoProvider.js	83.87% <0%> (-0.98%)	⬇️
src/CordovaCheck.js	86.66% <0%> (-0.84%)	⬇️
src/ActionStack.js	93.54% <0%> (-0.74%)	⬇️
src/FileUpdater.js	85.38% <0%> (-0.63%)	⬇️
src/PluginManager.js	91.83% <0%> (-0.62%)	⬇️
src/events.js	95% <0%> (-0.46%)	⬇️
... and 9 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e79ef47...d70fd6f. Read the comment docs.