Implement a cross-platform, no-toolbox UD/TCP send

[gian-didom]

Currently, S-Functions need a binary .mexXXX file that is platform-dependent. This means that the generated S-Functions are not cross-platform.
Current possible solutions:

• Use multiple UDP/TCP send/receive blocks according to the three main platform type (Linux, Windows, MacOS). However, we must make sure to cover all the possible systems.
• Code the TCP/UDP receive/send block as S-function builder blocks. This means that the entire code goes in the S-Function builder block. The block could be potentially copy-pasted and configured with the proper libraries that need to be linked (if any). At runtime, Simulink compiles the S-Functions, generates the .tlc, .c, and wrapper.c files and runs the simulation.