Flexible Port Binding for Transfer Module

[AdityaSripal]

Description

Allows transfer module to bind to portID =/= "transfer" by specifying the portID in the genesis state.

Removes check in channel callbacks

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For contributor use:

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer

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For admin use:

• Added appropriate labels to PR (ex. WIP, R4R, docs, etc)
• Reviewers assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #6011 into master will decrease coverage by 0.02%.
The diff coverage is 32.14%.

@@            Coverage Diff             @@
##           master    #6011      +/-   ##
==========================================
- Coverage   55.32%   55.29%   -0.03%     
==========================================
  Files         428      429       +1     
  Lines       25548    25562      +14     
==========================================
+ Hits        14134    14135       +1     
- Misses      10441    10454      +13     
  Partials      973      973              

[fedekunze]

Thanks @AdityaSripal !

[cwgoes]

ACK modulo @fedekunze comments

[fedekunze]

utACK