Add depth buffer

- Add depth testing to swapchain
- Add Shader abstraction
- Add CommandBuffer abstraction

Vulkan/res/shaders/shader.frag

@@ -1,12 +1,15 @@
 #version 450
 
-layout(set = 1, binding = 0) uniform sampler2D texSampler;
+layout(set = 0, binding = 1) uniform sampler2D texSampler;
 
 layout(location = 0) in vec3 fragColor;
 layout(location = 1) in vec2 fragTexCoord;
+layout(location = 2) in vec3 fragPosition;
+layout(location = 3) in vec3 fragLightPos;
 
 layout(location = 0) out vec4 outColor;
 
 void main() {
-    outColor = vec4(fragColor, 1.0) * texture(texSampler, fragTexCoord);
+    float scale = 0.45 +  max(dot(vec3(0, 1, 0), normalize(fragLightPos - fragPosition)), 0.0);
+    outColor = vec4(fragColor, 1.0) * texture(texSampler, fragTexCoord) * scale;
 }