Allow configurable stacktrace encoding

[arwineap]

This PR adds a StacktraceEncoder type to the EncoderConfig struct

Users can override the EncodeStacktrace field to configure how stacktraces are outputed This PR aims to resolve https://github.com/uber-go/zap/issues/514 by mirroring the behavior of the EncodeCaller field

The EncodeStacktrace field has been inserted as a required field, and has been added to NewDevelopmentConfig and NewProductionConfig as sane defaults however, as a required field it can cause a panic if a user is manually building their config without these helpers.

[CLAassistant]

All committers have signed the CLA.

[codecov[bot]]

Codecov Report

Merging #1371 (cad62a8) into master (87577d8) will decrease coverage by 0.13%. The diff coverage is 84.12%.

:exclamation: Current head cad62a8 differs from pull request most recent head d45920a. Consider uploading reports for the commit d45920a to get more accurate results

@@            Coverage Diff             @@
##           master    #1371      +/-   ##
==========================================
- Coverage   98.28%   98.15%   -0.13%     
==========================================
  Files          53       53              
  Lines        3493     3527      +34     
==========================================
+ Hits         3433     3462      +29     
- Misses         50       55       +5     
  Partials       10       10              

Files	Coverage Δ
config.go	100.00% <100.00%> (ø)
zapcore/json_encoder.go	100.00% <100.00%> (ø)
zapcore/console_encoder.go	97.05% <78.57%> (-2.95%)	:arrow_down:
zapcore/encoder.go	83.45% <22.22%> (-4.24%)	:arrow_down:

... and 1 file with indirect coverage changes

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[arwineap]

Thank you for the clarification, I'm unsure how I missed the default catch for the nil cases. This has been added.

One other concern I had was with the console encoder; I'm not sure I can avoid calling getSliceEncoder() a second time because of the split in output between structured fields and unstructured panic data. This felt ineffecient, but the code seems cleaner than the alternative

[abhinav]

Related: We'll want to make a decision on https://github.com/uber-go/zap/issues/1373 before we release this because choices there affect the design for this.

[devdrops]

@abhinav @arwineap hi! Any news about this PR? Responses are really appreciated :slightly_smiling_face:

[arwineap]

I will work to rebase this with modern changes; but depending on any decision in https://github.com/uber-go/zap/issues/1373 we may try to send the entire stack object into the function instead of the string