Allow framework users to navigate to an external URL using TurboNavigator

[olivaresf]

Exposing this function is a convenience so that, for common use cases, a framework user can open an external URL by using TurboNavigator, instead of implementing these functions themselves.

Session behavior when an external URL is found is unchanged.

[joemasilotti]

Good idea! I made one suggestion on the documentation and the API. Let me know what you think.

[joemasilotti]

Suggested change

	public func open(externalURL: URL, _ via: ExternalURLNavigationAction) {
	public func open(externalURL url: URL, via action: ExternalURLNavigationAction) {

If via isn't optional then I think we should expose the name in the function.

[olivaresf]

I don't have a strong preference. The reason I removed the label is because of call readability:

open(anExternalURL, via: .openViaSafariController)

vs.

open(anExternalURL, .openViaSafariController)

I don't mind either way. If you still feel the label works, can you commit your own suggestion? (I don't know if Github allows that, if not, I can merge it!)

[joemasilotti]

Thanks for writing this out! I'm now thinking we should change the enum so usage can read more fluently.

open(externalURL, via: .safariViewController)
open(externalURL, via: .system)

If that sounds good let me know and I'll make a commit locally and push.

[olivaresf]

Since we're now using ExternalURLNavigationAction in two places (handle(externalURL:) and open(externalURL:_:)) one of them will have their readability suffer.

For example, using .viaSafariViewController will read well in the former, but not the latter:

func handle(externalURL: URL) -> ExternalURLNavigationAction {
    .openViaSafariViewController
}

open(externalURL, via: .openViaSafariViewController)

vs.

func handle(externalURL: URL) -> ExternalURLNavigationAction {
    .safariViewController
}

open(externalURL, via: .safariViewController)

My preference is including openVia in the enum case names. This is such a small change that we should go with whichever. I wanted to point out though, that both use cases have different grammar.

[olivaresf]

@joemasilotti will merge this in as-is. If we decide on a name change, we can do another PR.