Move Robolectric snapshot repository config to common_library_config

This means it gets pulled in when apps depend on ExoPlayer locally:
https://github.com/google/ExoPlayer/blob/release-v2/README.md#locally

This resolves the missing snapshot error that people see currently,
because the existing repository config is in the top-level ExoPlayer
build.gradle file which isn't executed when depending on ExoPlayer
locally.

Issue: google#8332
Issue: google#7932
PiperOrigin-RevId: 347245078

build.gradle

@@ -26,7 +26,6 @@ allprojects {
  repositories {
  google()
  jcenter()
- maven { url "https://oss.sonatype.org/content/repositories/snapshots" }
  }
  project.ext {
  exoplayerPublishEnabled = false

common_library_config.gradle

@@ -15,6 +15,12 @@
 apply from: "$gradle.ext.exoplayerSettingsDir/constants.gradle"
 apply plugin: 'com.android.library'
 
+repositories {
+ // TODO(internal b/169753382): Remove this when we no longer depend on
+ // Robolectric snapshots.
+ maven { url "https://oss.sonatype.org/content/repositories/snapshots" }
+}
+
 android {
  compileSdkVersion project.ext.compileSdkVersion