JetBrains: Ignore bin files that are generated by VS Code extension

Created by: philipp-spiess

I've been setting up Java support in VS Code and it seems that the extension caches some artifacts in client/jetbrains/bin. I don't want to commit these mistakenly so adding it to the gitignore.

It seems like the setup already works in VS Code so that's cool 😎

Test plan

Ensured that bin/ files are no longer added by git add .

App preview:

• Web
• Storybook

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