Upgrade DrawerLayout to 1.2.0 and simplify code

[cbeyls]

The main benefit of upgrading to version 1.2.0 of DrawerLayout is to properly support predictive back animations: when initiating a back gesture on API 33+, the DrawerLayout will animate automatically.

In addition to the upgrade, simplify DrawerLayout integration:

• Forward key events to the DrawerLayout so it can intercept them and close itself when needed.
• Don't handle the DrawerLayout closing manually using the OnBackPressedCallback anymore. This is not necessary since the back event will now be intercepted by the DrawerLayout when needed before reaching the OnBackPressedDispatcher.
• Remove legacy fix for DrawerLayout staying open after Activity recreation.