refactor: Move React SDK to this repo and consolidate Javascript SDK packages to depend on local versions of each other

[zashraf1985]

Summary

Javascript SDK uses released versions of sub packages. This makes it difficult to work on features that need to change multiple sub packages. This PR consolidates all the sub packages to use local versions of each other. Additionally, we are also mobing React-SDK to this repo and make it dependent on the local version of Javascript-SDK.

Test plan

• All the existing Unit tests should pass
• All the existing FSC tests should pass

[zashraf1985]

Can we reference the folders instead of adding packed archives.

[zashraf1985]

Instead of re-organizaing and moving packages. i am thinking along these lines.

1. Keep the package structure of this repo as it is. Just change the references / dependencies to include event-processor, datafile-manager, logging and utils through relative path. Please do not use npm pack, simply refer to the folder path of the package in dependencies.
2. Make build through lerna from root. This means running npm run build on the root folder should build all the packages in the sub folders.
3. In react-sdk, instead of moving contents of react-sdk, simply add this repo as sub module and then use local copy of javascript SDK there as a dependency instead of released version.

[zashraf1985]

Looks Great!. Here are a few additional things to do,

1. You have changed the dependencies in optimizely-sdk to relative paths which is correct. This also needs to be done in other packages. I believe all the other packages at least use utils and probably logging too. can you update those to relative paths too.
2. Git Submodule should not be used in this repo. We should keep react SDK in its own repo and use git sub module there to include commit from javascript master and refer locally. Which means you should fork the react-sdk repo just like you did this one, add a branch, add javascript-sdk as submodule and refer it locally.
3. When you did npm install, did it change the package-lock.json files? if yes, then please commit those too.