Add project icon for `IntelliJ IDEA`

[Pankraz76]

Before this PR

After this PR

==COMMIT_MSG== ==COMMIT_MSG==

Possible downsides?

• https://github.com/diffplug/spotless/pull/2522

[palantirtech]

Thanks for your interest in palantir/palantir-java-format, @Pankraz76! Before we can accept your pull request, you need to sign our contributor license agreement - just visit https://cla.palantir.com/ and follow the instructions. Once you sign, I'll automatically update this pull request.

[changelog-app[bot]]

Generate changelog in changelog/@unreleased

Type (Select exactly one)

• [ ] Feature (Adding new functionality)
• [ ] Improvement (Improving existing functionality)
• [ ] Fix (Fixing an issue with existing functionality)
• [ ] Break (Creating a new major version by breaking public APIs)
• [ ] Deprecation (Removing functionality in a non-breaking way)
• [ ] Migration (Automatically moving data/functionality to a new system)

Description Add project icon for IntelliJ IDEA

Check the box to generate changelog(s)

• [ ] Generate changelog entry