tus-js-client v5 major release

[Acconut]

The last major release (v4) was only 10 months ago, but it didn't include massive changes and only dropped support for old Node.js version. For the next major release (v5) I have some larger changes in mind that helps prepare tus-js-client for the future while also making its usage more resilient to errors:

• Move the package to TypeScript: Move to TypeScript #683
• Decide whether we want to continue to dual-publish and if we can take advantage of the new exports syntax: Refresh export structure in package.json #693
• Check if there are old Node.js version we can drop support for
• Consider renaming the browser environment to web
• Think about how we can offer environment-specific features (e.g. only in React Native)
• Use a state machine inside tus.Upload to avoid starting an upload twice, for example. Allow users to query the state.

[mkabatek]

These sound like some awesome changes! esp:

Use a state machine inside tus.Upload to avoid starting an upload twice, for example. Allow users to query the state.