Organize fragments based on user navigation patterns in journey graph

[abhaysood]

Problem

Journey graph does not reflect navigation pattern of users for single Activity apps which only contain Fragments or ones which heavily rely on Fragments.

Solution

Fragments in journey graph should reflect typical user navigation pattern similar to activities.

Alternatives

If this cannot be constructed automatically based on lifecycle events, we could consider adding manual events (like navigation or screen view events to aid in constructing the graph).

Tasks

1. Use parent fragment to build journey graph
   Backend — Add fragments in journey graphs #1231
   Android — feat(android): add parent fragment to fragment lifecycle events #1262
2. Add screen view event
   Add screen view event #1263
3. Auto instrument androidx-navigation:fragment library to send screen view events
   Auto instrument androidx-navigation:fragment  #1264

[abhaysood]

Update Summary

We've been exploring ways to infer the navigation graph using fragment lifecycle events, but the results weren't as reliable as we'd hoped. Instead of shipping something unpredictable, we've decided to take a different approach. We'll automate what we're confident about and give developers more control over the rest of the graph using custom events.
Here's our plan moving forward:

• Activity navigation will be shown using lifecycle events, as it is today.
• For fragments, we'll use Fragment.getParentFragment to show the hierarchy when it's available. If it's not, we'll connect fragments directly to the activity. — feat(android): add parent fragment to fragment lifecycle events #1262
• We're going to add a new "screen_view" event to help build the journey graph — Add screen view event #1263
• Good news for those using androidx-navigation:fragment or androidx-navigation:compose libraries - we'll auto-instrument these to collect the "screen_view" events. With the ability to turn it off if needed. — Auto instrument androidx-navigation:fragment  #1264

We think this approach will give us more accurate results while keeping things flexible for developers.