Update dependencies

1st commit

• Update gradle wrapper to 6.5 using git bash

2nd commit

• Group dependencies

3rd commit

• Comment out currently unused libsuperuser
• Update commons-io 2.6 -> 2.7 (changelog)
• Update RxJava 1.3.6 -> 1.3.8 (changelog)
• Update Tracedroid 1.4 -> 3.0 (changelog)
• Update Jackson 2.9.9 -> 2.9.10 (changelog)
• Update Mockito 2.28.2 -> 3.3.3 (changelog)
• Fix a Robolectric deprecation

4th commit

• Update RxJava1 1.3.8 -> RxJava2 2.2.19 (changelog)
  • https://github.com/ReactiveX/RxJava/wiki/What's-different-in-2.0

5th commit

• Merge master

6th commit

• A bunch of the tests are all sorts of broken. I fixed some of them by downgrading Robolectric to 3.0. Also completed the last AndroidX migration.