Use Apple's GitHub Workflows linting script

[MahdiBM]

The script is configured to respect a .swiftformatignore file which I'll need for Penny.
swift-format might soon have this ability in itself: swiftlang/swift-format#873

[gwynne]

Really? A spurious newline?

[MahdiBM]

I actually can't find out why this wasn't reported before. This is needed based on how swift-format behaves.

Did some tests locally, it would sometimes randomly emit a warning about this, and sometimes not.
I couldn't find out what makes it care about that line, and what makes it not. Tried different configurations as well
...

[gwynne]

I'm strongly against needing the newline, frankly... If swift-format is demanding it, to me that's a bug in swift-format. Imports should be grouped together unless there are a lot of them and they fall naturally into sectioning.

[MahdiBM]

We are at a point of "it is what it is" with swift-format. I'd suggest you give up as well. The configuration that Apple repos use also has the same behavior IIRC.

I think it requires the new line because the next import is a @testable one.

[gwynne]

Yeah, obviously it does but to me it's visually jarring and completely pointless to have that gap. Why should @testable imports be separated?

(I know, I know, swift-format isn't gonna change... but there should really be more control.)

[gwynne]

I must say there are a lot of ways in which I don't like the direction swift-format has taken. For all its issues, swiftformat always impressed me more with its flexibility.