chore: Organize Messenger tests

[Gudahtt]

Explanation

The Messenger tests for actions and events have each been moved into a describe block. Additionally, test descriptions have been updated to avoid starting with "should", in accordance with our test naming conventions.

References

N/A

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, highlighting breaking changes as necessary
• I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes

[Gudahtt]

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