Change: `iOSApplicationExtension` → `iOS` in specifying platform.

[fummicc1]

Title

Change: iOSApplicationExtension → iOS in specifying platform.

Motivation

I changed iOSApplicationExtension specifier into iOS because it failed to compile on Xcode14.

Task Description

In this state, I cloud not find the official reason why this change is necessary, but ordinarily iOSApplicationExtension should be used for app extensions like Share Extension, Notiication Extension and so on. That's why it is better to specify iOS platform availability than iOSApplicationExtension, I think.

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Thank you for reading this proposal.