Avoid needing the Android Context in Sentry.init(..) common code

[buenaflor]

Problem

Sentry Android init needs the Android context: SentryAndroid.init(context) { } which is not easily replicated in the common code.

Our current solution involves a hacky workaround that declares an expect class in commonCode which typealiases to Android context on Android but does nothing on iOS.

common: expect abstract class Context
android: actual typealias Context
iOS: actual abstract class Context

Avoiding context would also mean the user doesn't need to specifically create another init function just for the context which removes some of the burden on them.

Solution

A user pointed to an article/blog with a possible solution for this in discussions: #112

The article: https://proandroiddev.com/how-to-avoid-asking-for-android-context-in-kotlin-multiplatform-libraries-api-d280a4adebd2

Essentially what we would be going to use is the androidx.startup:startup-runtime package which handles the initialization before the library code - repo

Update:
This can be implemented using a simple internal ContentProvider on KMP Android. The incorporation of the startup library is still something that is being discussed.

[buenaflor]

Merged in #117