refactor: Break navigation dependency cycles with :core:navigation

[nikclayton]

The previous code generally started an activity by having the activity provide a method in a companion object that returns the relevant intent, possibly taking additional parameters that will be included in the intent as extras.

E.g., if A wants to start B, B provides the method that returns the intent that starts B.

This introduces a dependency between A and B.

This is worse if B also wants to start A.

For example, if A is StatusListActivity and B isViewThreadActivity. The user might click a status in StatusListActivity to view the thread, starting ViewThreadActivity. But from the thread they might click a hashtag to view the list of statuses with that hashtag. Now StatusListActivity and ViewThreadActivity have a circular dependency.

Even if that doesn't happen the dependency means that any changes to B will trigger a rebuild of A, even if the changes to B are not relevant.

Break this dependency by adding a :core:navigation module with an app.pachli.core.navigation package that contains Intent subclasses that should be used instead. The quadrant plugin is used to generate constants that can be used to launch activities by name instead of by class, breaking the dependency chain.

The plugin uses the Activity names from the manifest, so when an activity is moved in the future the constant will automatically update to reflect the new package name.

If the activity's intent requires specific extras those are passed via the constructor, with companion object methods to extract them from the intent.

Using the intent classes from this package is enforced by a lint IntentDetector which will warn if any intents are created using a class literal.