Settings submenus should have up/back button

I am using the Wallabag app on a Supernote e-ink device, which does not have a physical back button. I ran into an issue where I navigate into a Settings submenu (hamburger icon > Settings > any menu, i.e. Connection) but cannot navigate back out because there is no 'up' button as I expect in the upper left corner of the screen. I have to force kill the application and relaunch it in order to get back to the main screen.

I considered posting this as a comment in issue https://github.com/wallabag/android-app/issues/168, however I think it should stand alone as a separate issue since [Google Material Design guidelines](https://m2.material.io/design/navigation/understanding-navigation.html#reverse-navigation) make the following recommendation:

> Upward navigation should be implemented for all child screens in an app and follow platform guidance. Android and web apps should use the Material Up action ...

[Here's a link to an image from the design guidelines page](https://lh3.googleusercontent.com/pK8fp2NFvyA0sTLpI7U7rJaBcbV1QvfG38mL6ZOvh8WKSRRyqfOEoexSx9T_D871RFvaor5eMVS0gv-T_vypGcl25R6nEyDIclmJ=w1064-v0) demonstrating how I believe it should be implemented.

Thanks!