exchanges: shift GetDefaultConfig wrapper function to exchange.go

[shazbert]

PR Description

Shifts GetDefaultConfig wrapper function to exchange.go

Mitigates potential issue when its called in a wrapper test and overwrites memory after initial SetDefault method func is called.

Also RMs a bunch of code wrapper side which is nice but its signature is a tad janky. Optionally we can disconnect it as a method and just have an exported function.

Type of change

Please delete options that are not relevant and add an x in [] as item is complete.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

How has this been tested

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration and also consider improving test coverage whilst working on a certain feature or package.

• [ ] go test ./... -race
• [ ] golangci-lint run
• [ ] Test X

Checklist

• [ ] My code follows the style guidelines of this project
• [ ] I have performed a self-review of my own code
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation and regenerated documentation via the documentation tool
• [ ] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] New and existing unit tests pass locally and on Github Actions with my changes
• [ ] Any dependent changes have been merged and published in downstream modules

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 66.66667% with 10 lines in your changes are missing coverage. Please review.

Project coverage is 35.96%. Comparing base (d679a76) to head (bbd1f09). Report is 8 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1472      +/-   ##
==========================================
+ Coverage   35.89%   35.96%   +0.06%     
==========================================
  Files         411      411              
  Lines      177595   177227     -368     
==========================================
- Hits        63752    63734      -18     
+ Misses     106058   105705     -353     
- Partials     7785     7788       +3     

Files	Coverage Δ
backtester/engine/live.go	83.08% <100.00%> (+0.20%)	:arrow_up:
backtester/engine/setup.go	57.84% <100.00%> (ø)
engine/helpers.go	80.10% <100.00%> (ø)
exchanges/alphapoint/alphapoint_wrapper.go	23.64% <ø> (+0.29%)	:arrow_up:
exchanges/binance/binance_wrapper.go	38.45% <ø> (+0.23%)	:arrow_up:
exchanges/binanceus/binanceus_wrapper.go	40.90% <ø> (+0.83%)	:arrow_up:
exchanges/bitfinex/bitfinex_wrapper.go	37.16% <ø> (+0.58%)	:arrow_up:
exchanges/bitflyer/bitflyer_wrapper.go	35.66% <ø> (+1.80%)	:arrow_up:
exchanges/bithumb/bithumb_wrapper.go	38.61% <ø> (+0.92%)	:arrow_up:
exchanges/bitmex/bitmex_wrapper.go	44.67% <ø> (-0.54%)	:arrow_down:
... and 21 more

... and 10 files with indirect coverage changes