Fixes react-codemirror tests

[anderson4j]

The problem:
Running e2e tests in the react-codemirror package fails on main with a message like:
SyntaxError: Named export 'testData' not found. The requested module '@neo4j-cypher/language-support' is a CommonJS module, which may not support all module.exports as named exports.
This testData file is part of the language-support package, and we use an ESModule import to access it in the react-codemirror tests.

The fix:
Adding "type": "module" in the package.json of language-support makes it so .js files (the ones we build with the build-esm-and-types script) are treated as ESModule instead of CommonJS.
In the build-commonjs script the output file is already .cjs instead of .js so this should not interfere with the actual CommonJS file.

Although this allows us to run the react-codemirror playwright tests, they often ran out of memory, which is the reason for the change to how much memory nodejs has access to in the e2e scripts.

Even with these changes and the tests running, it seems like the e2e tests are quite flaky locally

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[anderson4j]

I tried this locally after Oskar's tip, and it does seem to improve flakiness, if not fully fixing it...
Not sure how true this is though, trying to think of a good way to measure it