feat: Upgrade iOS deployment target to iOS 12

[sebaland]

Description of changes:
This PR updates the iOS deployment target version to iOS 12 to all the pods that had it at iOS 9.

Xcode 15's minimum deployment target is iOS 9, so attempting to use any of the products resulted in a warning

The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 9.0, but the range of supported deployment target versions is 12.0 to 17.2.99.

Bumping the version also reveals a couple of deprecation warnings, so I've fixed the ones that were simple fixes (e.g. SFAuthenticationSession -> ASWebAuthenticationSession).

• Related PR: feat(AWSCore): Upgrading CocoaLumberjack to version 3.8.4 #5222

Check points:

• Added new tests to cover change, if needed
• All unit tests pass
• All integration tests pass
• Updated CHANGELOG.md
• Documentation update for the change if required
• PR title conforms to conventional commit style

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.