Feature/migrate to typescript

[DanOnCall]

Please see the Changelog.md file for an outline of the changes this PR introduces. In summary:

• Migrate to TypeScript.
• Add support for Express v5.x.x.
• Improve testing.
• Align API with express-jwt.
• Bump version to 3.0.0.

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Testing Done

The existing test suite was migrated to TypeScript and expanded to validate all new and existing functionality. All tests pass successfully.

The testing strategy includes:

• Full API Coverage: Validated all public functions and configuration options, including checkAllScopes, customUserKey, customScopeKey, and failWithError.
• Authorization Logic: Confirmed correct handling of "any" vs. "all" scope checks, for both string-based and array-based scope claims in the JWT.
• Robust Error Handling: Ensured that all documented error scenarios—such as insufficient scope, malformed JWT payloads, or invalid scope formats—produce the correct 403 error response or call next(err) as expected.
• Express Compatibility: The full test suite was executed against both Express v4 and Express v5 to guarantee compatibility.
• Static Type-Checking: The entire project, including tests, now passes strict TypeScript validation, ensuring the new type definitions are accurate and effective.

This ensures the v3.0.0 release is robust, type-safe, and backward-compatible with supported Express versions.