feat(nexus): gmp events metadata (#2189)

[haiyizxx]

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 91.17647% with 3 lines in your changes missing coverage. Please review.

Project coverage is 39.13%. Comparing base (2a8810a) to head (798132a).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
x/axelarnet/message_handler.go	76.92%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2199      +/-   ##
==========================================
- Coverage   39.16%   39.13%   -0.04%     
==========================================
  Files         373      373              
  Lines       31699    37216    +5517     
==========================================
+ Hits        12414    14563    +2149     
- Misses      18349    21717    +3368     
  Partials      936      936              

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[kyanokashi]

Need to just sort out dependencies