Re-add repositories{} block to allow for build-from-source

Summary:
I've just tested the nightly and the build from source is broken as the `repositories{}` block is missing.

Normally RNGP will take care of setting repositories for everyone, but this is triggered by the app-module.
When building from source, the app module of the user is isolated from the included build of React Native,
therefore the repositories{} definitions are not passed over.

Without this, the build fails with:
```
Cannot resolve external dependency ... because no repositories are defined
```

Changelog:
[Internal] [Changed] - Re-add repositories{} block to allow for build-from-source

Reviewed By: cipolleschi

Differential Revision: D43501011

fbshipit-source-id: b41c56c62839163ad210e7e303940dec0a9001da

ReactAndroid/build.gradle

@@ -418,6 +418,14 @@ task installArchives {
     dependsOn("publishAllPublicationsToNpmRepository")
 }
 
+repositories {
+    // Normally RNGP will set repositories for all modules,
+    // but when consumed from source, we need to re-declare
+    // those repositories as there is no app module there.
+    mavenCentral()
+    google()
+}
+
 android {
     buildToolsVersion = "33.0.0"
     compileSdkVersion 33

ReactAndroid/hermes-engine/build.gradle

@@ -116,6 +116,14 @@ def reactNativeArchitectures() {
     return value ? value.split(",") : ["armeabi-v7a", "x86", "x86_64", "arm64-v8a"]
 }
 
+repositories {
+    // Normally RNGP will set repositories for all modules,
+    // but when consumed from source, we need to re-declare
+    // those repositories as there is no app module there.
+    mavenCentral()
+    google()
+}
+
 android {
     compileSdkVersion 31
     buildToolsVersion = "31.0.0"