Fix BLEUUID toString (#3289)

uuid16 is Missing first 4 characters.
uuid is Missing last 2 characters.

Author: tanakamasayuki

libraries/BLE/src/BLEUUID.cpp

@@ -352,8 +352,8 @@ std::string BLEUUID::toString() {
 	// If the UUIDs are 16 or 32 bit, pad correctly.
 
 	if (m_uuid.len == ESP_UUID_LEN_16) {  // If the UUID is 16bit, pad correctly.
-		char hex[5];
-		snprintf(hex, sizeof(hex), "%04x", m_uuid.uuid.uuid16);
+		char hex[9];
+		snprintf(hex, sizeof(hex), "%08x", m_uuid.uuid.uuid16);
 		return std::string(hex) + "-0000-1000-8000-00805f9b34fb";
 	} // End 16bit UUID