Relax fragment dependency

[breedx-splk]

This changes the dependency on navigation-fragment to compileOnly for all modules except fragment intsrumentation.

This should prevent a transitive dependency for users who do not use fragments, and doesn't force a newer version on users who might use an older version.

I tried the demo app, and it came up just fine. I believe that this is because the demo-app uses the agent, and the agent includes fragment instrumentation, so it picks up the transitive dependency as normal. It's a little worrying to have references to Fragment classes with a mere compileOnly(), so we should figure out what our end state should look like.

[marandaneto]

I think the only problem is if any classes that depend on the fragment lib try to be loaded/instantiated.
is that the case?
if so, we'd need to do reflection and check if the fragment lib is available at runtime before doing so:
eg

val clazz = "androidx.fragment.app.FragmentManager$FragmentLifecycleCallbacks"
val isFragmentAvailable = try Class.forName(clazz) catch ...
if (!isFragmentAvailable) return
// import and use android fragment classes

otherwise the app will crash at runtime

[bidetofevil]

Feels like some instrumentation, especially ones with special deps, should be pulled into its own module and can thus be not included for folks who don't want it.

[bidetofevil]

What remains of this should be handled in #961