Convert blob package to TypeScript

[jpstevens]

What?

This PR converts the blob package to TypeScript.

Why?

Ensures package is fully type checked.

How?

• converted files to .ts
• explicitly typed variables and functions in index file
• added @ts-ignore statements to tests that call functions in ways that are not type-compliant

Testing Instructions

npm run test:unit -- packages/blob tests pass npm run build:package-types returns a zero exit code

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Co-authored-by: sirreal <[email protected]>

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[sirreal]

👋 @jpstevens Thanks for this! If you'll update this PR on the latest trunk and address feedback we can likely give this a final review and land it.