Add .editorconfig and reformat the universe

[rohitsanj]

Summary of Changes

• Adds a .editorconfig file based on the IntelliJ Google Code Style XML -- this only defines configs for .java files. We may choose to add config for other file types down the line.
• Used the Reformat Code feature in IntelliJ to reformat all the files in the src/ directory.

[confluent-cla-assistant]

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