Add lodash merge to correctly extend current config file with default

[lucasbento]

Fix a bug on the CLI crashing when creating a type, basically it was trying to get the interface folder from the .graphqlrc file, it would crash if it didn’t exist.

Now it’s correctly working with a fallback.

[codecov-io]

Codecov Report

Merging #60 into master will increase coverage by -0.32%.

@@            Coverage Diff             @@
##           master      #60      +/-   ##
==========================================
- Coverage   83.41%   83.09%   -0.32%     
==========================================
  Files          13       13              
  Lines         211      213       +2     
==========================================
+ Hits          176      177       +1     
- Misses         35       36       +1

Impacted Files	Coverage Δ
packages/generator/src/utils.js	94.84% <60%> (-0.95%)	❌

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