2428: Remove manual multidexing, Jetifier & deprecated package attribute

[sarahsporck]

Short description

This PR removes some unused configurations from our gradle setup:

• Multidexing is enabled and run by default since sdk 21
• jetifier is deprecated & it is automatically run by the react-native cli, so no need to invoke it manually and keep the dependency... I still don't think that there is a place for jetifier anymore
• since gradle 7.3 the package name should not be set in the AndroidManifest anymore
  

Proposed changes

• remove jetifier
• remove multidexing
• remove package name

Resolved issues

Fixes: #2428

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[LeandraH]

I also see android.enableJetifier=true in the gradle.properties, does that one also have to go?

[sarahsporck]

I also see android.enableJetifier=true in the gradle.properties, does that one also have to go?

Sadly this cannot go yet, as some of our dependencies still use android.support libraries, and this migrates them to androidx.