Move ReachabilityUtils to WordPressShared

[mokagio]

Problem

As part of #24165, there are certain pieces that need to be moved which depend on ReachabilityUtils an helper object that is also shared with the apps targets.

Solution

• Rewrites ReachabilityUtils and the underlying ReachabilityAlert in Swift
• Moves them to WordPressShared

I considered moving it to a dedicated package because I thought it used the actual Reachability library, but that turned out not to be the case.

I considered ditching this utility that does not support injection or testing, but decided against it to focus on #24165 instead.

[dangermattic]

	4 Warnings
⚠️	Modules/Package.swift was changed without updating its corresponding Package.resolved. Please resolve the Swift packages as appropriate to your project setup (e.g. in Xcode or by running swift package resolve).
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📲 You can test the changes from this Pull Request in WordPress Alpha by scanning the QR code below to install the corresponding build.

	App Name	WordPress Alpha
	Configuration	Release-Alpha
	Build Number	pr24267-7faaf9b
	Version	25.8
	Bundle ID	org.wordpress.alpha
	Commit	7faaf9b
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[mokagio]

I feel like you could extract the AppDelegate.configureReachability() part to here too, so that you don't have to indirectly rely on the app delegate instance.

Thanks @crazytonyli I'll have a look 👀

[mokagio]

Notice this accesses Reachability. I think we could work on this further and hide the library altogether under ReachabilityUtils. That is, this could call a method on ReachabilityUtils instead—law of Demeter

[mokagio]

If this makes sense to you, I'll create an issue to address this once #24165 is "done"

[crazytonyli]

The Reachability library probably can be replaced with NWPath, but that's perhaps a story for another day.

[mokagio]

I converted the code here to pass the same Reachability instance, but I think we could omit it.

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:) name:kReachabilityChangedNotification];

From the docs:

The object that sends notifications to the observer. Specify a notification sender to deliver only notifications from this sender.

When nil, the notification center doesn’t use sender names as criteria for delivery.

The handler method does

- (void)reachabilityChanged:(NSNotification *)notification
{
    Reachability *reachability = notification.object;
    if (reachability.isReachable) {
        [self initStats];
    }
}

We could replace add the info about connectivity as userInfo in the Notification and then we'd be good.

[mokagio]

Mmm... this and the rest of the diff look like a bad rebase