refactor: transparent render (#14)

* fix(renderer): defer uniform location retrieval and add view matrix in outline rendering

* refactor(gameplay): encapsulate per-type vertex data into VertexData struct

* feat(rendering): separate transparent blocks into discard and blend modes

* feat(renderer): implement order-independent transparency

* fix(shaders): reduce alpha discard threshold to 0.8

assets/shaders/block_composite_v_shader.glsl

@@ -0,0 +1,11 @@
+#version 460
+
+layout (location = 0) in vec2 pos;
+layout (location = 1) in vec2 texCoord;
+
+out vec2 TexCoord;
+
+void main() {
+    gl_Position = vec4(pos.x, pos.y, 0.0, 1.0);
+    TexCoord = texCoord;
+}