Convert MetaMetricsController (implementation + tests) to TypeScript

[mcmire]

What is this about?

As a prerequisite for migrating MetaMetricsController to BaseController v2, and to support the TypeScript migration effort for the extension, we want to convert MetaMetricsController to TypeScript.

Scenario

No response

Design

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Technical Details

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Threat Modeling Framework

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Acceptance Criteria

• All functions and methods are annotated with argument and return types.
• All properties and free variables are annotated with types.
• # is used for private properties and methods instead of _.
• The test file is converted to TypeScript along with the implementation file.

Stakeholder review needed before the work gets merged

• Engineering (needed in most cases)
• Design
• Product
• QA (automation tests are required to pass before merging PRs but not all changes are covered by automation tests - please review if QA is needed beyond automation tests)
• Security
• Legal
• Marketing
• Management (please specify)
• Other (please specify)

References

• Convert partial level 2 files to typescript for contributing to metamask-controller.js #23018