Various load errors due to missing files

[akien-mga]

Trying to edit the current main commit d2f35ef in Godot 4.0-rc (6cde3fac328e97e66b1c12d386deb25af395e215), I get the following load errors (on the second editor run, the first one is full of errors like Godot tends to be when the .godot folder isn't there yet):

ERROR: Can't open file from path 'res://models/shared/shaders/screen_shader.gdshader'.
   at: get_file_as_bytes (core/io/file_access.cpp:699)
WARNING: res://Enemies/beetle_bot/materials/beetlebot_eyes_mat.tres:4 - ext_resource, invalid UID: uid://bvxkh2pa1nqdq - using text path instead: res://models/shared/textures/eye_mask.png
     at: load (scene/resources/resource_format_text.cpp:448)
ERROR: Resource file not found: res://models/shared/textures/eye_mask.png.
   at: _load (core/io/resource_loader.cpp:226)
ERROR: res://Enemies/beetle_bot/materials/beetlebot_eyes_mat.tres:15 - Parse Error: [ext_resource] referenced non-loaded resource at: res://models/shared/textures/eye_mask.png
   at: _parse_ext_resource (scene/resources/resource_format_text.cpp:174)
ERROR: res://Enemies/beetle_bot/materials/beetlebot_eyes_mat.tres:15 - Parse Error: [ext_resource] referenced non-loaded resource at: res://models/shared/textures/eye_mask.png
   at: load (scene/resources/resource_format_text.cpp:735)
ERROR: Failed loading resource: res://Enemies/beetle_bot/materials/beetlebot_eyes_mat.tres. Make sure resources have been imported by opening the project in the editor at least once.
   at: _load (core/io/resource_loader.cpp:221)
ERROR: res://Enemies/smoke_puff/smoke_ball.tres:4 - Parse Error: 
   at: load (scene/resources/resource_format_text.cpp:510)
ERROR: Failed loading resource: res://Enemies/smoke_puff/smoke_ball.tres. Make sure resources have been imported by opening the project in the editor at least once.
   at: _load (core/io/resource_loader.cpp:221)
WARNING: res://Player/Coin/CoinVisuals/CoinModel.tscn:3 - ext_resource, invalid UID: uid://dqbsd44l6f1xi - using text path instead: res://Player/Coin/CoinVisuals/CoinModel.glb
     at: load (scene/resources/resource_format_text.cpp:448)
WARNING: res://JumpingPad/JumpingPadVisuals/JumpingPadModel.tscn:3 - ext_resource, invalid UID: uid://n4c3p8bt5sb1 - using text path instead: res://JumpingPad/JumpingPadVisuals/JumpingPadModel.glb
     at: load (scene/resources/resource_format_text.cpp:448)
WARNING: res://Box/Box.tscn:4 - ext_resource, invalid UID: uid://cdtq6fyl7hhgm - using text path instead: res://Box/BoxVisuals/BoxModel.glb
     at: load (scene/resources/resource_format_text.cpp:448)

There's indeed no models folder in the repo.

[NathanLovato]

Fixed by #16 and/or #13