gateio: update FuturesAccount and Position struct

[shazbert]

PR Description

• Updates struct to include all fields and converts string fields that hold a float to types.Number for easier conversion.
• Fix bug that stopped transfers from anything outside of spot.
• Exported GateioTime -> Time so that it can be instantiable outside of package
• Addresses issue Bug in gateio_wrapper.go , it should be 'y' #1544

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

[codecov]

Codecov Report

Attention: Patch coverage is 27.77778% with 13 lines in your changes are missing coverage. Please review.

Project coverage is 37.80%. Comparing base (34ef09d) to head (3ccd883).
Report is 4 commits behind head on master.

❗ Current head 3ccd883 differs from pull request most recent head aa1aaac

Please upload reports for the commit aa1aaac to get more accurate results.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1532      +/-   ##
==========================================
+ Coverage   35.89%   37.80%   +1.90%     
==========================================
  Files         409      409              
  Lines      177453   147722   -29731     
==========================================
- Hits        63699    55846    -7853     
+ Misses     105899    84022   -21877     
+ Partials     7855     7854       -1     

Files	Coverage Δ
exchanges/gateio/gateio_types.go	71.42% <ø> (+5.71%)	⬆️
exchanges/gateio/gateio_convert.go	73.33% <83.33%> (+3.88%)	⬆️
exchanges/gateio/gateio_wrapper.go	42.84% <0.00%> (+3.29%)	⬆️
exchanges/gateio/gateio.go	16.33% <0.00%> (+2.13%)	⬆️

... and 383 files with indirect coverage changes

[shazbert]

Got an update to the fee struct coming through. PAUSE. 🙏

[shazbert]

It is now pushed you can all relax and get back to reviewing this massive PR. 👍