Support native assets in superfluid staking

[nicolaslara]

Closes: #XXX

What is the purpose of the change

Add a description of the overall background and high level changes that this PR introduces

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Testing and Verifying

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This change is a trivial rework / code cleanup without any test coverage.

(or)

This change is already covered by existing tests, such as (please describe tests).

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This change added tests and can be verified as follows:

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• Added unit test that validates ...
• Added integration tests for end-to-end deployment with ...
• Extended integration test for ...
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Documentation and Release Note

• [ ] Does this pull request introduce a new feature or user-facing behavior changes?
• [ ] Changelog entry added to Unreleased section of CHANGELOG.md?

Where is the change documented?

• [ ] Specification (x/{module}/README.md)
• [ ] Osmosis documentation site
• [ ] Code comments?
• [ ] N/A