Rename main.js to main.cjs

[Nick-Mazuk]

When a user's root-level package.json includes "type": "module", building with rules_swc produces the following error:

require('@swc/cli')
^

ReferenceError: require is not defined in ES module scope, you can use import instead

Renaming the main.js file to main.cjs resolves this issue.

See minimal reproduction of the issue: https://github.com/Nick-Mazuk/bazel-swc-es6

[CLAassistant]

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[alexeagle]

Thanks!