Gradle 7.0.3 + Kotlin 1.5.31 + RxJava 2.2.21 + AndroidX migration

[huuphuoc1396]

Hi @andreabresolin,
I read your article on medium. It's good to talk about RxJava and Coroutines performance. However, versions' Gradle, Kotlin and RxJava are too old, so I upgraded them to current to usage. You can review it and apply to your repository if it's helpful.

Changed:

• Build Gradle to 7.0.3
• Rip of jcenter(), changed to mavenCentral()
• Kotlin version to 1.5.31
• Kotlin coroutine version to 1.5.1
• RxJava2 to 2.2.21
• RxJava for Android to 2.1.1
• AndroidX Migration and using ViewBinding to replace synthetics