Add a method for obtaining display cutouts on Android

[madmiraal]

Adds get_display_cutouts method to DisplayServer to return an Array of Rect2 each of which is the bounding rectangle for a display cutout or notch. Display cutouts are non-functional areas on edge-to-edge screens used by cameras and sensors. Returns an empty array if the device does not have cutouts.

This PR only implements the method for Android. Other platforms will return an empty array.

Closes godotengine/godot-proposals#3466
Supersedes #54290

[akien-mga]

CC @bruvzg so you can check if the proposed API will be suitable for iOS / macOS notch too (which can be implemented in a follow-up PR).

[bruvzg]

so you can check if the proposed API will be suitable for iOS / macOS notch too (which can be implemented in a follow-up PR).

Yes, Array of Rect2 is suitable for macOS / iOS, but in case of macOS we actually do not need it at all, since default full-screen mode will account for the notch automatically.

[akien-mga]

Thanks!