Make it possible to use ExpensiMark in worklets

[tomekzaw]

This PR adds 'worklet'; directive in file ExpensiMark.ts (as well as some of its dependencies, namely str.ts and utils.ts) so that class ExpensiMark can be used instantiated and used in worklets.

When 'worklet'; directive is located at the top of the file, all functions, classes and object methods in the top-level scope of within this file are workletized.

Worklets are short-running JS functions that can be run on the UI thread. We need to run ExpensiMark on the UI thread synchronously as the user types inside MarkdownTextInput so we can format its contents synchronously.

Fixed Issues

$ Expensify/react-native-live-markdown#317

Tests

1. What unit/integration tests cover your change? What autoQA tests cover your change?
2. What tests did you perform that validates your changed worked?

QA

1. What does QA need to do to validate your changes?
2. What areas to they need to test for regressions?

[github-actions]

🚀Published to npm in v2.0.55