feat(minor-interchain-token-service): refactor chain registration

[cjcobb23]

• combine SetChainConfig and RegisterItsContract into single message
• add UpdateChain message

[codecov]

Codecov Report

Attention: Patch coverage is 99.32886% with 1 line in your changes missing coverage. Please review.

Project coverage is 93.49%. Comparing base (98acb3b) to head (79ccf56).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
contracts/interchain-token-service/src/msg.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #681      +/-   ##
==========================================
- Coverage   93.50%   93.49%   -0.02%     
==========================================
  Files         237      237              
  Lines       35132    35192      +60     
==========================================
+ Hits        32851    32903      +52     
- Misses       2281     2289       +8     

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