`isolation` should be after `mutators` in the default for `modifier_order`

[rgoldberg]

New Issue Checklist

• I've Updated SwiftLint to the latest version.
• I've searched for existing GitHub issues.

Feature or Enhancement Proposal

isolation should be after mutators in the default for modifier_order. Search for actor-isolation-modifier on https://docs.swift.org/swift-book/documentation/the-swift-programming-language/summaryofthegrammar.

I would imagine that the Swift language reference wouldn't consistently list actor-isolation-modifier after both access-level-modifier & mutation-modifier if they recommend that, e.g., nonisolated should be written before private.

[SimplyDanny]

Fair point. However, I wouldn't interpret too much into a grammar. It defines possibilities but doesn't recommend things and it especially doesn't specify order in this case.

We went with this default order because it's how most project put the modifiers. At least that's from my experience, which isn't massive in that regard, admittedly.

I'm also open to change it, but expect other reports afterwards. Not sure if that's worth the effort, also given that folks can just configure the order themselves if they don't agree to the default.