Updated Android Support Library to Android X library

[aitJess]

Description

Updated use of support library for annotations to the androidx library. This is due to the support library no longer being maintained and the androidx library replacing it.

Related Issue

https://github.com/Rolamix/cordova-plugin-playlist/issues/42

Motivation and Context

This change is required due to android's maintenance of the support library stopping, which may eventually lead to them deprecating the library. This is to future proof the plugin and allow it to work with other updated plugins.

How Has This Been Tested?

Since all it changed was the used libraries for certain function tags -- namely FloatRange, IntRange, NotNull, and Nullable -- I've tested it in my own cordova app and was able to successfully build with Android X Support.

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [X] Breaking change (fix or feature that would cause existing functionality to change) This would cause anyone updating to this latest version to no longer be able to use the plugin when Android X support is disabled.

Checklist:

• [X] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [X] I have read the CONTRIBUTING document.