feat: add support for .editorconfig

[okuuva]

Fixes #61.

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[braydonk]

Thanks for the PR, looks like a good start. Can you also add an integration test case that leverages a .editorconfig? The guidance for how to add a test case is here:
https://github.com/google/yamlfmt/blob/main/docs/integration-test.md#add-new-test-case

[braydonk]

I think this need a go mod tidy; not sure why it added this extra require block.

[okuuva]

Hmm, that's a good question. Another good one is why go mod tidy only touches go.sum...

[okuuva]

Thanks for the PR, looks like a good start. Can you also add an integration test case that leverages a .editorconfig? The guidance for how to add a test case is here: main/docs/integration-test.md#add-new-test-case

Sure! I'm just thinking that this probably isn't as straight forward as I thought. The "Automatic search for .editorconfig files" section of the readme implies that the config file should be checked for every formatted file separately, in case src/foo and src/foo/bar both have a separate .editorconfig file. In which case files under src/foo/bar should potentially be formatted differently than files under src/foo...

[okuuva]

Thanks for the PR, looks like a good start. Can you also add an integration test case that leverages a .editorconfig? The guidance for how to add a test case is here: main/docs/integration-test.md#add-new-test-case

Sure! I'm just thinking that this probably isn't as straight forward as I thought. The "Automatic search for .editorconfig files" section of the readme implies that the config file should be checked for every formatted file separately, in case src/foo and src/foo/bar both have a separate .editorconfig file. In which case files under src/foo/bar should potentially be formatted differently than files under src/foo...

Yup, that's the case. So basically .editorconfig support would require a feature that enables using a separate config per processed file. Looking at the code I can't see any clean way of implementing that. @braydonk is that something you'd be willing to include and support and if so, do you have any pointers on how exactly to do that? To be clear: I'm willing to do the work, just wanted to check with you first before starting such a big change.