Adopt JuliaFormatter.jl

[kbarros]

To ensure uniformity of the Sunny source code (and in accordance with BlueStyle) I think we should run all of our .jl files through JuliaFormatter.jl.

We should also set up Github actions so that JuliaFormatter runs automatically on every commit.

JuliaFormatter allows a lot of customization, but the defaults look like a good starting point.

Many of our comments involve formatted math equations, and these should not be re-wrapped. It is possible to disable formatting on local chunks of code as described here.

[kbarros]

Let's implement this only after the big outstanding PRs have been merged.

[kbarros]

Initial tests in #200.

The primary blocker is domluna/JuliaFormatter.jl#780. Are we willing to lose whitespace formatting around binary ops?

[kbarros]

As proposed by Eric Sabo on Slack, it might be possible to implement the solution to domluna/JuliaFormatter.jl#780 ourselves. That is, we could potentially preserve white space around binary operations by implementing a custom style. This custom style could follow Blue Style, but essentially disable the behavior of p_binaryop_call as defined here. As another reference, one could follow the implementation of the whitespace_ops_in_indices option.

The disadvantage, per Eric, is that:

you have to run [the new style] manually via the command line and you can’t import your new style guidelines into VSCode

Help wanted if anyone is interested in learning about this type of Julia hacking.