Support other platform sdks from generated xcode project.

[furby-tm]

• Namely, this supports the ability for a user to select iOS, visionOS, and tvOS devices from Xcode's run destinations with Xcode projects generated via swift bundler generate-xcode-project, which would otherwise cause the app to be built for the wrong device, macOS, and be unable to be launched from the user's selected run destination.
• This also allows calls to swift bundler's --platform switch to be synonymously called with apple platform sdk equivalents.

As an example:

swift bundler run --platform xros

Is now also exactly equivalent to:

swift bundler run --platform visionOS

[stackotter]

you thought you could get away with it...

[furby-tm]

@stackotter Attempted to run a swiftformat . and got 134 files formatted 😅. Would you like to issue that in your own commit once this is merged in?

Oh gross, I just noticed you are using apple's swift format, I use this one, would just require you to slap in a new .swiftformat file so that the formatter respects your formatting settings.

Copying over your existing settings with a .swiftformat file at the root of your repo with:

--indent 2
--indentcase true

Only changes 94 files (compared to 134) with far less changes.

[stackotter]

lgtm 🎉