Replace yuzu identifiers with citron

Update magic numbers and default identifiers across codebase:
- UUID default value
- Thread magic number
- Amiibo name
- Vulkan cache magic number
- Shader cache magic number

src/video_core/shader_environment.cpp

@@ -25,7 +25,7 @@
 
 namespace VideoCommon {
 
-constexpr std::array<char, 8> MAGIC_NUMBER{'y', 'u', 'z', 'u', 'c', 'a', 'c', 'h'};
+constexpr std::array<char, 8> MAGIC_NUMBER{'c', 'i', 't', 'r', 'c', 'a', 'c', 'h'};
 
 constexpr size_t INST_SIZE = sizeof(u64);