feat: add MsgSideChainStakeMigration and StakeMigrationApp

[pythonberg1997]

Description

This pr is to add MsgSideChainStakeMigration and StakeMigrationApp.

Changes

Notable changes:

• add MsgSideChainStakeMigration and StakeMigrationApp

[codecov-commenter]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (49902aa) 48.80% compared to head (6ac43b0) 48.80%.

Files	Patch %	Lines
app/app.go	22.22%	5 Missing and 2 partials ⚠️

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Additional details and impacted files

@@              Coverage Diff              @@
##           bc-fusion     #993      +/-   ##
=============================================
- Coverage      48.80%   48.80%   -0.01%     
=============================================
  Files            127      127              
  Lines          12802    12811       +9     
=============================================
+ Hits            6248     6252       +4     
- Misses          6124     6127       +3     
- Partials         430      432       +2     

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