feat: [IOPLT-384] Removes Mixpanel community library to use the official npm package

[CrisTofani]

Short description

This PR want to remove the legacy Mixpanel community library and replaces it with the mixpanel-react-native npm package

[!note] Push notification initialization for Mixpanel has been removed since it is actually not supported by the react-native wrapper and is planned to be deprecated by native-sdk as per https://github.com/mixpanel/mixpanel-react-native/issues/89#issuecomment-904192090

List of changes proposed in this pull request

• Changes the library
• Remap the initializagtion file
• Fix compilation issues due to the change of library

How to test

Chack mixpanel events are correctly dispatched and tracked