Evaluate discontinuing development/ support of the non-core packages

[gajus]

Currently, this monorepo consists of:

• babel-plugin-flow-prepack
• babel-plugin-flow-runtime
• flow-config-parser
• flow-runtime-cli
• flow-runtime-docs
• flow-runtime-mobx
• flow-runtime-validators
• flow-runtime

A subset of these provide the core functionality of flow-runtime:

• flow-runtime-validators
• flow-runtime
• flow-runtime-cli
• babel-plugin-flow-runtime

Meanwhile, the other packages could equally exist on their own:

• babel-plugin-flow-prepack
• flow-config-parser
• flow-runtime-mobx

I suggest that in order to keep the repository structure simple, we discontinue support of the latter 3 packages in this repository.

Unless there are any objections or arguments against, I will add this to TODO list.

[goodmind]

Related to flowconfig parser, I wanted to support it from Flow's side facebook/flow#7698
But there's some problems with LICENSE

[goodmind]

Actually most of the projects depends of flow-config-parser