Upgrade build configuration to use sdk 31 instead

[vincent-paing]

Fixes #327.

Upgrade example and the library project to compile with Sdk version 31 (Android 12). This also added required exported flag in AndroidManifest.xml. I believe there's no reason for external apps to open ChromeTabsManagerActivity, so the exported flag here should be false.

BREAKING CHANGES: By default, it will now use Android 31, so the library user have to upgrade if they don't provide required gradle ext values. I believe this won't impact much since most react native project already specify those sdk versions. Or they could also use override version in AndroidManifest.xml

<uses-sdk android:targetSdkVersion="{VERSION}"
 tools:overrideLibrary="com.proyecto26.inappbrowser"/>

[jdnichollsc]

Hey dude, thanks for your contribution!

As I can see this is not a breaking change, they can define these versions from android/build.gradle as we already explain in the README of the project. If you want I can merge these changes, but again I don't see a breaking change here 🤔

Best,
Juan

[vincent-paing]

Sure in that case, feel free to merge it @jdnichollsc