feat(uniond): upgrade cosmos sdk to v0.50.2 (#1072)

- Upgraded the ref of our cosmos-sdk fork
- Re-vendored
- Replaced deprecated `vendorSha256` with recommended `vendorHash`
throughout the repository

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## Summary by CodeRabbit

- **Refactor**
- Replaced `vendorSha256` with `vendorHash` in multiple files for
improved hash handling and build configuration.
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