Update dependencies for a modern SDK

[BenRacicot]

After digging into the SDK and the API I've noticed several issues and some true roadblocks for front-end web applications.

1. Webpack 5: The SDK currently uses Webpack 4.33.0. This is a roadblock for all modern apps and frameworks (WP 5 environments)
2. TypeScript 4.5+: TypeScript 3.4.5 is outdated and an optimized TS developer experience is healthy, safer and easier for everyone.
3. Fallbacks, updates or recommendations: Eventsource and Webpack 4 is a roadblock [732] in a Webpack 5 world. Itself and its deps must be polyfilled. This is a compounded issue because the SDK's version 1.0.7 (> 4 years old) would likely require polys that match this version.
4. BigNumber: Just spent an hour debugging rt.times(...).greaterThan is not a function which was fixed by falling back to "bignumber.js": "7.2.1" from 9.0.2

[BenRacicot]

I finally got Angular polly'd to get the SDK operational. I'm very surprised at how stale this technology is. Perhaps @Shaptic would be willing to discuss this in depth? I'm doing something pretty cool at wallethack.com.

Really hope this issue gets the attention it needs from leads at SDF.

[Shaptic]

I'm going to close this issue as closed in v9.0.0-beta. Please reopen (or, better yet, comment on #584) if there is more you'd like to see.