Improve tests and update dependencies

[Mikescops]

This pull request introduces several updates to the native-keychain project, including migrating ESLint configuration to a modern format, enhancing test coverage, and updating dependencies. The changes improve maintainability, modernize tooling, and refine the project's testing and build processes.

ESLint Configuration Migration:

• Removed .eslintrc.json and replaced it with eslint.config.js, adopting the flat config format for ESLint. This includes updated plugin imports, parser settings, and rules for TypeScript and Prettier integration. [1] [2]

Testing Enhancements:

• Overhauled tests/index.ts to include structured test cases for biometric support, password operations (with and without biometry), and cleanup procedures. Added utility functions for logging and assertions to improve test readability and maintainability.

Dependency Updates:

• Updated package.json dependencies to newer versions, including koffi, TypeScript, ESLint, and Prettier. Replaced ts-node with tsx for running tests. [1] [2]
• Added "type": "module" to package.json to enable ES module support.

Codebase Modernization:

• Modified imports in src/index.ts to use ES module syntax and added __filename and __dirname definitions for compatibility with Node.js modules. Updated function return types for getPassword and requestBiometricsVerification to infer types directly. [1] [2] [3]

Documentation Updates:

• Enhanced README.md with sections on development, including instructions for running tests, building the project, and linting. Added details about biometric authentication requirements during testing.