Docs: Add useSWC documentation as alternative to Babel

[jonniebigodes]

With this pull request, the documentation was updated to feature the experimental flag useSwc as an alternative to Babel.

Follows up on #22075 and addresses #22678

What was done:

• Updated the documentation to feature in the feature flag and reference it as a fallback for issues with Babel
• Created the required snippets

Leaving out the patch label to avoid issues with the documentation being published, as it seems that this flag is only available for 7.1.

[jonniebigodes]

Thanks for taking the time to review this @ndelangen. Appreciate it 🙏 . Merging

[benedfit]

Am I right in assuming there is currently no way to provide additional config to swc-loader in the same way as is possible with babel-loader? I'm currently using a non-standard swc.config.js file, rather than .swcrc, (due to the needs of a plugin), so I don't have a means of passing this config to Storybook

[ndelangen]

AFAICS plugins can be used in .swcrc: https://swc.rs/docs/configuration/compilation#jscexperimentalplugins

We could add a way to explicitly configure the swc-loader via main.ts for sure, though if not needed, I'd rather not.
I can't find a config option in their docs to set the configFile to a custom path for the swc-loader: https://swc.rs/docs/usage/swc-loader

[benedfit]

@swc/plugin-relay currently needs rootDir: __dirname and as a result the config can't be in the usual JSON format. So everywhere I'm using swc-loader I'm explicitly passing in the contents of my config file. e.g.

const swcConfig = require("./.swcrc.js")

// ...

{
  include: path.resolve("./src"),
  test: /\.ts$/,
  use: [
    {
      loader: "swc-loader",
      options: swcConfig,
    },
  ],
}