Problem: app is sealed before upgrade handler is called

[thomas-nguy]

👮🏻👮🏻👮🏻 !!!! REFERENCE THE PROBLEM YOUR ARE SOLVING IN THE PR TITLE AND DESCRIBE YOUR SOLUTION HERE !!!! DO NOT FORGET !!!! 👮🏻👮🏻👮🏻

Solution: Move the upgrade handler before sealing the app

PR Checklist:

• Have you read the CONTRIBUTING.md?
• Does your PR follow the C4 patch requirements?
• Have you rebased your work on top of the latest master?
• Have you checked your code compiles? (make)
• Have you included tests for any non-trivial functionality?
• Have you checked your code passes the unit tests? (make test)
• Have you checked your code formatting is correct? (go fmt)
• Have you checked your basic code style is fine? (golangci-lint run)
• If you added any dependencies, have you checked they do not contain any known vulnerabilities? (go list -json -m all | nancy sleuth)
• If your changes affect the client infrastructure, have you run the integration test?
• If your changes affect public APIs, does your PR follow the C4 evolution of public contracts?
• If your code changes public APIs, have you incremented the crate version numbers and documented your changes in the CHANGELOG.md?
• If you are contributing for the first time, please read the agreement in CONTRIBUTING.md now and add a comment to this pull request stating that your PR is in accordance with the Developer's Certificate of Origin.

Thank you for your code, it's appreciated! :)

[codecov]

Codecov Report

Merging #287 (ae29be4) into main (3ea70c5) will increase coverage by 19.59%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##             main     #287       +/-   ##
===========================================
+ Coverage   21.51%   41.11%   +19.59%     
===========================================
  Files          27       30        +3     
  Lines        1729     1508      -221     
===========================================
+ Hits          372      620      +248     
+ Misses       1324      842      -482     
- Partials       33       46       +13     

Impacted Files	Coverage Δ
x/cronos/genesis.go	61.53% <ø> (-38.47%)	⬇️
x/cronos/handler.go	100.00% <ø> (ø)
x/cronos/keeper/evm.go	56.31% <ø> (+4.58%)	⬆️
x/cronos/keeper/evm_hooks.go	90.00% <ø> (ø)
x/cronos/keeper/evm_log_handlers.go	83.50% <ø> (ø)
x/cronos/keeper/gravity_hooks.go	0.00% <ø> (ø)
x/cronos/keeper/grpc_query.go	0.00% <ø> (ø)
x/cronos/keeper/ibc.go	83.20% <ø> (+5.01%)	⬆️
x/cronos/keeper/ibc_hooks.go	50.00% <ø> (-8.83%)	⬇️
x/cronos/keeper/keeper.go	64.89% <ø> (-29.45%)	⬇️
... and 28 more

[tomtau]

lgtm -- one thing is the integration test, but there's a separate issue for it: #247