Updates "@babel/preset-react" preset "runtime" param to "automatic" and cleans up import lines

[sagemintblue]

While working through the Relay tutorial and its "newsfeed" example [1] I was confused by some seemingly unused import lines in tsx files of the following form:

import * as React from "react";

My VSCode configuration enables removal of unused imports when files are saved, so this line was being removed. This led to a runtime error of the form:

ReferenceError: React is not defined

Some searching lead me to the new JSX Transform announcement [2] which suggested that most of these React import lines are no longer needed. After further reading I found docs for the "@babel/preset-react" Babel preset [3] which suggest that the runtime parameter should be automatic (instead of classic, the default value) to ensure the functions that JSX transpiles to are automatically imported. This change did the trick for me. After cleaning up the import lines across most tsx files in the newsfeed project it still builds and runs without issue for me.

[1] https://relay.dev/docs/tutorial/intro/
[2] https://legacy.reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html
[3] https://babeljs.io/docs/babel-preset-react

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