render: implement a vulkan renderer

src/gfx_apis/vulkan/shaders/tex.frag

@@ -0,0 +1,9 @@
+#version 450
+
+layout(set = 0, binding = 0) uniform sampler2D tex;
+layout(location = 0) in vec2 tex_pos;
+layout(location = 0) out vec4 out_color;
+
+void main() {
+	out_color = textureLod(tex, tex_pos, 0);
+}