[ios][shellApps] Rebuild all supported shellApps with Xcode 12.1

[bbarthec]

Motivation and Context

As turtle v1 is going to use Xcode 12.1 we have to update all the iOS shellApps to be pre-build with the very Xcode version.

Description

standalone shellApps:

• [x] sdk 36
• [x] sdk 37
• [x] sdk 38
• [x] sdk 39

AdHoc Client Shell App:

• [x] done

[bbarthec]

I've performed some testing using new iOS shellApps build with Xcode 12.1.

I've done some smoke testing following SDKs using simulator builds of native-component-list app:

• [x] SDK 36
• [x] SDK 37
• [x] SDK 38

And additionally I've made full QA using SDK 39 native-component-list standalone build on TestFlight.