[jest-plugin] Use transformer config options

[stagas]

This PR adds the functionality for the jest plugin transformer to use transformer configuration options defined in jest.config.

In short, this works now:

module.exports = {
  ...
  transform: {
    "\\.(js|jsx|ts|tsx)$": [
      "@sucrase/jest-plugin",
      { jsxPragma: "h", jsxFragment: "Fragment" }
    ],
  ...
}

Notes

Tests are not included as I couldn't find where to put them.

Manually I tested both cases of passing and not passing a config. In the latter case Jest simply sends an empty object {} so the spread operation must be safe.

[alangpierce]

Sorry for not getting to this originally! This was also implemented very similarly in #749, which was just merged, so I'll close this PR and also mention this PR as well in the release notes.