Fix to support Cordova 10

[okhiroyuki]

To support Cordova 10, the following two fixes have been made.

• minSdkVersion 21 to 22
• Handling of jniLibs in Gradle 4

minSdkVersion 21 to 22

Cordova Android 9 has been modified to reflect the change in minSdkVersion to 22.

Android Version Support Update

• The default target SDK version is set to 29.
• The minimum SDK version is set to 22.
• The minimum supported Android version is 5.1.
  NOTE : because Cordova has increased the minimum SDK version to 22, we no longer support or test with Android 5.0 or lower.

https://cordova.apache.org/announcements/2020/06/29/cordova-android-9.0.0.html

Handling of jniLibs in Gradle 4

Since Gradle 4.0, jniLibs has been removed as it is no longer needed.

refs: https://developer.android.com/studio/releases/gradle-plugin#cmake-imported-targets

Fix to check GradleVersion instead of simply deleting it.

error message

> Task :app:mergeDebugNativeLibs FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:mergeDebugNativeLibs'.
> A failure occurred while executing com.android.build.gradle.internal.tasks.Workers$ActionFacade
   > More than one file was found with OS independent path 'lib/arm64-v8a/libnode.so'. If you are using jniLibs and CMake IMPORTED targets, see https://developer.android.com/studio/preview/features#automatic_packaging_of_prebuilt_dependencies_used_by_cmake

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

Deprecated Gradle features were used in this build, making it incompatible with Gradle 7.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/6.5/userguide/command_line_interface.html#sec:command_line_warnings

BUILD FAILED in 20s
41 actionable tasks: 8 executed, 33 up-to-date

[okhiroyuki]

@semidark
Thank you for your feedback.
fix it.

[jaimecbernardo]

LGTM!
Thank you for the contribution and sorry for taking so long to get back to you.