chore(ios): upgrade iOS SDK to 17 - requires Xcode 15 - by April 29, 2024

[mcdurdin]

Apple writes:

We identified one or more issues with a recent delivery for your app, "Keyman" 17.0.258 (0.10662.10333). Your delivery was successful, but you may wish to correct the following issues in your next delivery:

ITMS-90725: SDK version issue - This app was built with the iOS 16.2 SDK. Starting April 29, 2024, all iOS and iPadOS apps must be built with the iOS 17 SDK or later, included in Xcode 15 or later, in order to be uploaded to App Store Connect or submitted for distribution.

[jahorton]

See #11215: there's a task we wanted to do on it but are currently unable to.

#11215 (comment)

In particular, that webView.isInspectable = true would be a very nice thing to have on our TestFlight builds. Inspection of keyboard internals within Keyman and FV apps on iOS 16.4+ and 17.0+ requires this flag to be set... but it's not even defined/declared in the SDK for our build agents' current version of Xcode.

[jahorton]

I've now spun off the iOS part of #11215 into #11229; we can revisit the latter once this issue is addressed.

[mcdurdin]

We have a working build agent and changes to the source for this are in place. I am going to go ahead and mark this as done.