Add packet struct write

protocol-generator/test/packet_struct.txt

@@ -0,0 +1,27 @@
+pub struct TestPacket {
+    pub boolean: bool,
+    pub byte: i8,
+    pub unsigned_byte: u8,
+    pub short: i16,
+    pub unsigned_short: u16,
+    pub int: i32,
+    #[packet(with = "var_int")]
+    pub varint: i32,
+    pub unsigned_int: u32,
+    pub long: i64,
+    #[packet(with = "var_long")]
+    pub varlong: i64,
+    pub unsigned_long: u64,
+    pub float: f32,
+    pub double: f64,
+    #[packet(max_length = 20)]
+    pub string: String,
+    pub uuid: Uuid,
+    #[packet(with = "uuid_hyp_str")]
+    pub hyphenated: Uuid,
+    pub byte_array: Vec<u8>,
+    #[packet(with = "rest")]
+    pub rest: Vec<u8>,
+    pub compound_tag: CompoundTag,
+    pub ref: Chat,
+}