Android: Standardize the use of application id and namespace

[vaslabs]

This PR standardises the use of application id and namespace. It is also one of the pre-requisites of making hilt instrumented tests to work.

The application id is a unique id for every android app , so the android manifest package depends on it.

The android manifest package is also used whenever there's a relative path for Applications and activities so

<manifest package="com.foo">
    <application android:name=".TodoApplication"/>
</manifest>

Becomes

<manifest package="com.foo">
    <application android:name="com.foo.TodoApplication"/>
</manifest>

During manifest merging. Because this happens when the manifest is loaded (before everything is merged) we start with the manifest package being the android namespace. We then pass the package property to the merger to be the application id (the package for each up is unique). This is what appears to be happening in AGP as well. (It is also the reason why I was confused when reverse engineering the AGP behaviour and was alternating between namespace and application id)

I've also cleaned up some of the xml manual modifications that are not needed anymore as are handled by the merger tool

[vaslabs]

I think the job failures are not related to these changes

[lihaoyi]

Looks good to me, happy to merge when you;re done with this

[vaslabs]

Looks good to me, happy to merge when you;re done with this

Yes, it's ready