patterns: Add a pattern for Roblox .pack files (#435)

* Added the .pack format

* Clarified some fields by changing the naming

patterns/roblox_pack.hexpat

@@ -0,0 +1,33 @@
+#pragma author marduk.ru
+#pragma description Roblox .pack shader archive format
+#pragma magic [ 52 42 58 53 ] @ 0x00
+
+import std.string;
+import hex.core;
+import type.magic;
+
+struct Header {
+    type::Magic<"RBXS"> magic;
+    u32 fileCount;
+};
+
+struct FileIndex {
+    char name[0x40];
+    u128 md5Hash;
+    u32  offset;
+    u32  size;
+    u64  reserved;
+    
+    u8 file[size] @ offset;
+    
+    #ifdef __IMHEX__
+    hex::core::add_virtual_file(name, file);
+    #endif
+} [[name(name)]];
+
+struct RBXPack {
+    Header header;
+    FileIndex files[header.fileCount];
+};
+
+RBXPack pack @ 0x0;