`rendering/quality/shadows` is now `rendering/quality/positional_shadow`
to explicitly denote that the settings only affect positional light shadows,
not directional light shadows.
Shadow atlas settings now contain the word "atlas" for easier searching.
Soft shadow quality settings were renamed to contain the word "filter".
This makes the settings appear when searching for "filter" in the
project settings dialog, like in Godot 3.x.
21ea1c3835