Add configuration to ignore function declaration on line_length rule

[serejahh]

Some native frameworks have really long delegate methods. For example:

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey : Any]? = nil) -> Bool {
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView 

And breaking the lines by parameters makes the declaration ugly. Especially when a body is less a declaration

It'd be useful to have a rule which warns about a too long line of code but excludes lines with functions declarations. What do you think?

[marcelofabri]

Maybe this should be a configuration of line_length rule? See #598 for another proposed configuration.

[serejahh]

Looks like a possible solution

[mlwelles]

I took a pass at his and just submitted a pull request: #1264

[marcelofabri]

Fixed by @mlwelles in #1264! 🎉