Upgrade TwilioVideo in Android to 7.3.1 (#632)

* Upgrade TwilioVideo in Android to 7.3.1

> Support for 6.x will cease on September 17th, 2022. This branch will only receive fixes for critical issues until that date.

## Migration Docs
Link: https://www.twilio.com/docs/video/migrating-6x-7x

So far nothing important:
- the inclusion of `frames_encoded` in the returned data is not included in this PR
- I don't think the ordering of `onAudioTrackSubscribed` and `onVideoTrackSubscribed` ever mattered?


## Changes:
- Minimum SDK will now be 21 instead of 16
  - Update also bumped Google WebRTC to 1.0.32006 from 1.0.30039


# Tests

I have so far tested this with web-windows (I'll find time to test calls between ios and android):
```
Web:
- Windows 11 HSL 21H2 22000.918
- Google Chrome Version 105.0.5195.102 (Official Build) (64-bit)


Androids:
[1]: Huawei Y7a (PPA-LX2) EMUI 10.1.1 Android 10
[2]: Galaxy A71 (SM-A715F/DS) One UI 4.1 Android 12
[3]: Huawei nova 3i (INE-LX2) EMUI 9.1.1 Android 9
[4]: vivo Y85A Funtouch OS_4.0 Android 8.1.0

```


If anyone can double check, that would be greatly appreciated

* Update build.gradle

Bad value provided for DEFAULT_COMPILE_SDK_VERSION (39 -> 30)

Author: marqroldan

android/build.gradle

@@ -1,10 +1,10 @@
 apply plugin: 'com.android.library'
 
-def DEFAULT_COMPILE_SDK_VERSION             = 27
+def DEFAULT_COMPILE_SDK_VERSION             = 30
 def DEFAULT_BUILD_TOOLS_VERSION             = "27.0.3"
-def DEFAULT_TARGET_SDK_VERSION              = 27
+def DEFAULT_TARGET_SDK_VERSION              = 30
 def DEFAULT_ANDROID_SUPPORT_VERSION         = "27.1.0"
-def DEFAULT_ANDROID_MIN_SDK_VERSION         = 16
+def DEFAULT_ANDROID_MIN_SDK_VERSION         = 21
 
 android {
     compileSdkVersion rootProject.hasProperty('compileSdkVersion') ? rootProject.compileSdkVersion : DEFAULT_COMPILE_SDK_VERSION
@@ -50,7 +50,7 @@ dependencies {
 
     implementation fileTree(dir: 'libs', include: ['*.jar'])
     implementation "com.android.support:appcompat-v7:$androidSupportVersion"
-    implementation "com.twilio:video-android:6.2.1"
-    implementation 'org.webrtc:google-webrtc:1.0.30039'
+    implementation "com.twilio:video-android:7.3.1"
+    implementation 'org.webrtc:google-webrtc:1.0.32006'
     implementation "com.facebook.react:react-native:+"  // From node_modules
 }