feat: migrate to typescript

This is initial Pull Request with the goal of having brand new, simplified API & native TS support. The change contains few main areas:

I've used the code from @partheseas fork as suggested, with some clean up in the structure
- I've re-did the build system to fit TS package management - using rollup to build the bundle
- Repo structure has been changed - we don't need monorepo for the 2 projects here, and it would only mean pain in the release process, considering the e2e package was private and without dependencies
- I've started with some basic e2e test of the current implementation: simple main & render thread stores synced together and the counter component that updates visuals on both render & main
- Added typescript types compatibility test agains basic redux usage. We also should consider extending it with applyMiddleware and other usages that might be breaking.
- And ofc GH action to build & test it all so far.

Target branch of this PR is v2 - follow up PRs would setup the semantic-release to help with the deployment process and the v2 branch would be considered an alpha version.

The code itself from my look at it is still rough on the edges and needs some work, I've even added some TODO: comments in the most obvious places, but overall I believe the goal should to be to polish it on the v2 branch with incremental refactors/fixes/tests.

klarna / electron-redux

feat: migrate to typescript #259