Convert AppStateController (implementation + tests) to TypeScript

[mcmire]

What is this about?

As a prerequisite for migrating AppStateController to BaseController v2, and to support the TypeScript migration effort for the extension, we want to convert AppStateController to TypeScript along with its tests.

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.
• Relevant types from app-state.d.ts are folded into app-state.ts.
• # 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 3 files to typescript for contributing to metamask-controller.js #23017