chore: Add .editorconfig to set default whitespacing rules

[xezon]

• Merge after refactor(format): Remove trailing whitespace from game code files #1425

This change adds a .editorconfig file to set default whitespacing rules.

[xezon]

I noticed that the trim_trailing_whitespace = true will remove not just whitespaces in the new lines written, but in all lines on document save (depending on the editor). So I think we would need to make a pass and remove all trailing whitespace first, to not get into situations where new changes edit unrelated whitespaces in a file.

[xezon]

Ok I have prepared a change that removes trailing spacespace: #1425

It is quite a massive change...

[xezon]

Whitespace fixes merged to main branch. Rebased. I will test once more if behavior is ok now.

[xezon]

The "trim_trailing_whitespace" works in Visual Studio Code, but appears to not work in Visual Studio 2022. But I guess it is ok for now.