[Mellanox] Adding SKU Mellanox-SN5600-C256

[DavidZagury]

Why I did it

Support Mellanox-SN5600-C256

Work item tracking

• Microsoft ADO (number only):

How I did it

Add relevant files to support the new SKU

How to verify it

Regression test

Which release branch to backport (provide reason below if selected)

• [ ] 201811
• [ ] 201911
• [ ] 202006
• [ ] 202012
• [ ] 202106
• [ ] 202111
• [ ] 202205
• [ ] 202211
• [ ] 202305

Tested branch (Please provide the tested image version)

• [ ]
• [ ]

Description for the changelog

Link to config_db schema for YANG module changes

A picture of a cute animal (not mandatory but encouraged)