Fix Fork Support

[GalRogozinski]

Description

• [x] Change "chain" to "network"
• [x] Fork Data should be stored by Network struct instead of domain.
• [ ] We should have more bytes available for fork version.
• [ ] we should designate bytes for message version
• [ ] Investigate how to change the order of bytes in the domain

[GalRogozinski]

@olegshmuelov please comment here on any ideas or hardships that you are currently experiencing