feat: MUSD-107 added mUSD conversion transaction type

[Matt561]

Explanation

Small PR to add musdConversion to transaction-controller's TransactionType enum.

References

• MUSD-107: Add mUSD conversion transaction type to transaction controller

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Adds musdConversion to the TransactionType enum and updates the changelog.

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