Connect to standalone React Devtools

There has been discussion for a while about how to best connect React-lua to Devtools. #14 is a proof-of-concept Devtools implementation as a Roblox Studio plugin, but a better approach would be to connect React-lua directly to existing Devtools implementations.

This issue will focus on the Roblox use case because it's the only environment with a renderer currently written for React-lua.

Two(?) parts are required for a successful implementation:

• A Roblox Studio plugin that provides an interface for connecting to Devtools and selecting a React tree to debug.
• An external "bridge" application that connects Roblox to React Devtools. This is required because Roblox cannot open socket connections, which is how Devtools communicates. Roblox can communicate to the bridge via HTTP long polling.

This approach would also make it possible to use Devtools remotely on a live game client, as long as the Roblox side of the implementation is also exposed as a library. The bridge endpoint for Roblox would have to be exposed on the open internet.

This is still very early in planning, so if anyone has any thoughts or ideas, please share them in the replies.

No source files, tests, or entry points are named. Start by reviewing the proposed Roblox Studio plugin and external bridge, including the HTTP long-polling connection to React Devtools; the work is done when a React tree can be selected and debugged through the standalone Devtools implementation.