fix(nexus): coin type should be ICS20 if the coin is from external cosmos chain

[fish-sammy]

Description

Todos

• Unit tests
• Manual tests
• Documentation
• Connect epics/issues
• Tag type of change
• Upgrade handler

Steps to Test

Expected Behaviour

Other Notes

[codecov]

Codecov Report

Attention: Patch coverage is 91.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 39.21%. Comparing base (57ecd83) to head (da162d5).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
x/nexus/keeper/lockable_asset.go	91.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2194   +/-   ##
=======================================
  Coverage   39.20%   39.21%           
=======================================
  Files         373      373           
  Lines       31726    31731    +5     
=======================================
+ Hits        12439    12444    +5     
- Misses      18346    18347    +1     
+ Partials      941      940    -1     

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