Use `android:gravity="center_horizontal"`

Test: ./run_all_tests.sh

Also add `android.enableJetifier=true` for consistency across all projects.

Test: ./run_all_tests.sh

And the requisite Gradle 5.6.4

Test: ./run_all_tests.sh

Test: ./gradlew test

`javaClass.classLoader` is nullable in API 29.

Test: ./run_all_tests.sh

Rely on the `buildToolsVersion` that is bundled with the version of Android Gradle Plugin.

Test: ./run_all_tests.sh

Test: ./run_all_tests.sh

Test: ./run_all_tests.sh

Test: ./run_all_tests.sh

Test: ./run_all_tests.sh

Allow for incrementally updating the `compileSdkVersion` before upgrading the `targetSdkVersion`. In this case, they are both API 29 so this is a no-op.

Test: ./run_all_tests.sh

Test: ./run_all_tests.sh

DataBinding can observe `LiveData` directly as long as you call `setLifecycleOwner()`.

Test: ./gradlew cC

Fixes #802

Prevent drift between arch.testing and the runtime dependencies.

Fixes #801

Test: in the PersistenceMigrationsSample, ran ./gradlew cC

* Initial commit ViewBindingSample

* Adds first version of the sample and migrates gradle files to our versioning system

* Updates copyright headers and adds simple UI test

* Adds View Binding sample to circleCI config

* Typing in the wrong window apparently

* Reverts to API 28 for now

* Adds bind API to View Binding sample

Instead of starting a new `observe` call every time the query button is pressed, we should just update our current source of data by using `Transformations.switchMap`. We store the user's query in a `SavedStateHandle` to ensure that we handle process death and recreation properly (and to take advantage of the `getLiveData()` method to drive our `switchMap`.

Test: tests still pass

Fixes #759

- Export the schema
- Switch to `@SuppressWarnings` to suppress warnings at the compiler level
- Remove `android.databinding.enableV2=true` since V1 has been removed

Fixes #324

Fixes #367

Unnecessary try/catch?

Increase page size in PagingSample

Fixes #325

AndroidX Transition 1.2.0 is required for apps that target API 29 or higher and AndroidX Transition 1.3.0 is needed to take full advantage of the changes in Fragment 1.2.0.

Test: ./run_all_tests.sh

Instead of requiring `RedditActivity` to save and restore the selected subreddit, use `SavedStateHandle` and `AbstractSavedStateViewModelFactory` in `SubRedditViewModel` to allow the ViewModel to save and restore its own saved instance state.

Test: ./run_all_tests.sh
Test: ran PagingWithNetworkSample

- Activity 1.0.0 -> 1.1.0
- Fragment 1.2.0-rc05 -> 1.2.0
- Lifecycle 2.2.0-rc03 -> 2.2.0
- Navigation 2.2.0-rc04 -> 2.2.0

Test: ./run_all_tests.sh

Removes Network Paging sample from CI

Sort the dependencies alphabetically to make it more consistent when adding new dependencies.

Test: ./run_all_tests.sh

Make it more clear that each artifact group is independent from one another.

Test: ./run_all_tests.sh

Remove the overly broad "support" version and instead provide a separate, explicit version for each group of artifacts.

Test: ./run_all_tests.sh

Test: ./run_all_tests.sh

Use its replacement, `androidx.test.ext.junit.runners.AndroidJUnit4` from the `androidx.test.ext:junit` dependency.

Test: ./run_all_tests.sh

Instead of requiring each Fragment to redirect `findNavController()` through a `navController()` method that can be overridden in tests, use `Navigation.setViewNavController()` to control what NavController is found by `findNavController()`, allowing us to remove the `@OpenForTesting` annotation on each Fragment and the `navController()` method.

Test: Ran the GithubBrowserSample

[Fragment `1.1.0`](https://developer.android.com/jetpack/androidx/releases/fragment#version_110_3) added support for `postponeEnterTransition()` with a timeout, allowing us to avoid needing to directly use `postDelayed`.

Test: Ran the GithubBrowserSample

Test: ./run_all_tests.sh

Test: ./run_all_tests.sh

The stated purpose of onActivityCreated() is to wait until the activity is created. That isn't needed here, where what we're actually doing is setting up the binding with the ViewModel, making this more suitable for onViewCreated(). As onActivityCreated() and onViewCreated() happen back to back, there's no actual difference in behavior (just increased clarity on what we're doing).

Provide type safety to map and switchMap methods by using the respective Kotlin extension methods rather than Transformations.map and Transformations.switchMap.

Test: Ran the GithubBrowserSample