Add CacheData struct for representation of the reading/writing data
Create Package class instead the CacheData struct
ClientWrap: Use object of the Package class
Answer: Add GetSize method
Fix building errors in the Client and RegistrarClient classes
Fix building errors in the tests
Fix the checking data size in the read_test
Remove the unused MsgDataFree function
Package: Add the FreeData method
Use FreeData method of the Package class instead the free() function