exchanges/request: abstract and consolidate rate limiting code to request package

[shazbert]

PR Description

Pulled from initial draft #1151

• Allows context cancellation to occur while routine is being rate limited for any outbound REST request
• Reduces wrapper code size and bespoke implementations
• Fixes a couple of endpoints defaulting to unauth rates [BUG]

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)
• 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

[gloriousCode]

Cool! Only basic things that I could see.

[gloriousCode]

Thanks for making those changes!

[gloriousCode]

tACK! rate limiter still functioning

(rate limit at 1.991s with all pairs enabled)

[codecov]

Codecov Report

Attention: Patch coverage is 95.55215% with 29 lines in your changes are missing coverage. Please review.

Project coverage is 35.97%. Comparing base (34ef09d) to head (e4ca46c).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1477      +/-   ##
==========================================
+ Coverage   35.89%   35.97%   +0.07%     
==========================================
  Files         409      409              
  Lines      177453   176414    -1039     
==========================================
- Hits        63699    63464     -235     
+ Misses     105899   105101     -798     
+ Partials     7855     7849       -6     

Files	Coverage Δ
currency/coinmarketcap/coinmarketcap.go	55.33% <100.00%> (ø)
exchanges/binance/binance_cfutures.go	33.55% <100.00%> (ø)
exchanges/binance/binance_wrapper.go	38.45% <100.00%> (-0.08%)	⬇️
exchanges/binance/ratelimit.go	96.51% <100.00%> (+30.32%)	⬆️
exchanges/binance/type_convert.go	56.36% <ø> (+2.76%)	⬆️
exchanges/binanceus/binanceus_wrapper.go	40.89% <100.00%> (ø)
exchanges/binanceus/ratelimit.go	84.84% <100.00%> (+35.64%)	⬆️
exchanges/bitfinex/bitfinex_wrapper.go	37.95% <100.00%> (+0.09%)	⬆️
exchanges/bitfinex/ratelimit.go	100.00% <100.00%> (+53.33%)	⬆️
exchanges/bitflyer/bitflyer.go	50.31% <100.00%> (ø)
... and 47 more

... and 9 files with indirect coverage changes