Bithumb: Add subscription configuration

[gbjk]

Bithumb

• Add subscription configuration

New Library Dependencies

• sprig ( Also included in 4 other template PRs )

Type of change

• New feature (non-breaking change which adds functionality)

[codecov]

Codecov Report

Attention: Patch coverage is 87.50000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 36.36%. Comparing base (225429b) to head (56a820f).
Report is 45 commits behind head on master.

Files with missing lines	Patch %	Lines
exchanges/bithumb/bithumb_websocket.go	86.95%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1618   +/-   ##
=======================================
  Coverage   36.36%   36.36%           
=======================================
  Files         422      422           
  Lines      183105   183099    -6     
=======================================
+ Hits        66588    66589    +1     
+ Misses     108475   108472    -3     
+ Partials     8042     8038    -4     

Files with missing lines	Coverage Δ
exchanges/bithumb/bithumb_wrapper.go	29.78% <100.00%> (+0.10%)	⬆️
exchanges/subscription/subscription.go	100.00% <ø> (ø)
exchanges/bithumb/bithumb_websocket.go	50.33% <86.95%> (+6.02%)	⬆️

... and 18 files with indirect coverage changes

[shazbert]

tACK. I can see why the add for extra dependency; I am on the fence to add this just for mustToJson but it makes templating a lot easier.