plugin.xml should be able to add attribute to an existing element in AndroidManifest.xml

We have a need for a plugin we develop to add the attribute android:name to the <application> element to be able to point to a Class that tracks app sessions for analytics.

plugin.xml only support via <config-file> only to add elements to AndroidManfist.xml this request is to add an enhancement to also handle adding an attribute to an existing element.