implement player poses (sneak/sprint)

* Added sending player metadata with poses to everyone

* Renamed sendPlayerMetadataToAll to broadcastPlayerMetadata

* Made entity metadata system flexible

* Made broadcastPlayerMetadata create new metadata instead of using a global one

* Moved writeEntityData, sizeEntityData and sizeEntityMetadata to procedures

* style nitpicks

---------

Co-authored-by: p2r3 <p2r3@p2r3.com>

include/globals.h

@@ -248,6 +248,19 @@ typedef struct {
 
 #pragma pack(pop)
 
+union EntityDataValue {
+  uint8_t byte;
+  int pose;
+};
+
+typedef struct {
+  uint8_t index;
+  // 0 - Byte
+  // 21 - Pose
+  int type;
+  union EntityDataValue value;
+} EntityData;
+
 extern BlockChange block_changes[MAX_BLOCK_CHANGES];
 extern int block_changes_count;