A tutorial for how to install .APK from MAUI Android

### Description

Hi, I need to install .apk file from my MAUI application.
I found only some Xamarin tutorials.
The syntax of Xamarin and MAUI is not the same, I cannot figure out how to use the Xamarin example. I believe that the code must be now more simple in MAUI.
Could you please provide a way in the documentation on how to install an .apk file programmatically from inside a MAUI application?

Thank you.

### Public API Changes

Add documentation

### Intended Use-Case

Install .apk file from MAUI application (the MAUI application invokes an instalation of a .apk package).
Either install a companion app or install new version of existing app.

Review the Xamarin tutorials mentioned in the issue alongside the existing MAUI Android documentation. Document how a MAUI application can programmatically invoke installation of an APK, covering the companion-app and existing-app use cases; done means the procedure is clear enough to follow without relying on Xamarin syntax.

Written by the indexing model from the issue text.