Possible react-server-cli improvements

[jhnns]

While reviewing #791 and looking at the code-base, I realized that there are some possible improvements from my point of view. Here, I tried to sketch some changes that I think would be useful. Depending on your feedback and my personal schedule, I can also start with PRs.

Since it seems that you are pretty confident about #791, I'm going to assume here that #791 has already been merged.

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Separate and refactor webpack config

Moved to #795

Move express server to react-server

Moved to #796

Separate build code from runtime code

Moved to #797

Use multiple processes in development

Moved to #798

Nitpick: Rename __clientTemp and separate client and server build

Moved to #799

Nitpick: Remove __reactServerBase, __setReactServerBase and __reactServerManifest from window

Moved to #800

Nitpick: Remove compileOnly option

Moved to #801

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What do you think about these changes?

[doug-wade]

@jhnns I would definitely prefer to break this issue up into 7 separate issues -- trying to follow discussion in a single issue seems like it will quickly become overwhelming.

[doug-wade]

Thanks!