Test app iOS and Android version update and Android IAM display fixes

[spoorthipujariadobe]

Description

1. Removed languageVersion and apiVersion specified in flutter_aepmessaging gradle file to avoid conflicting with app's versions.
2. Removed FlutterAEPMessagingPlugin from extending FlutterActivity since its not required.
3. Added call to MobileCore.setApplication to FlutterAEPCorePlugin.onAttachedToEngine to avoid missing activity lifecycle. Note: We can instead ask app developer to add this call in their Application class
4. Changed MainActivity.kt in test app to extend FlutterFragmentActivity to fix in-app webview rendering issues. Need to test more around this before recommending customer's app to move to using it.
5. Updated Gradle, ACG and Kotlin version in Android test app to be compatible with latest version of flutter.
6. Updated iOS test app to target iOS 13

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[praveek]

Can you keep this and update it to 1.5 so that it matches what we use in native SDKs?

[spoorthipujariadobe]

Flutter gives a warning if the Kotlin compiler version is below 2.1.0 which only supports language version of 1.6. That's the minimum version I can set

[spoorthipujariadobe]

https://kotlinlang.org/docs/compatibility-guide-21.html#language

[cacheung]

What happen if the user uses higher Kotlin version than 1.5?

[spoorthipujariadobe]

The flutter bridge library can use features introduced in Kotlin 1.5 (or whatever version is specified). The actual compiler version used for the build is derived from the highest among all modules, the test app in this case, which is 2.1.0 and requires minimum language version of 1.6. The native SDKs are already compiled so it won't throw any errors. The flutter bridge code is not and thus the warnings.

[praveek]

Why is it 1.6? We are using 1.5 for our android SDKs.

[spoorthipujariadobe]

This is for the flutter Android bridge code, not the native SDK. Since latest version of flutter throws a warning when Kotlin Compiler version below 2.1.0 is used, I updated the languageVersion to the corresponding minimum supported version which is 1.6

[praveek]

I did not see your earlier comment.