Deprecate Vivado HLS

[bo3z]

Motivation
In many cases, we still include legacy support for Vivado HLS.

Describe the solution you'd like
Remove these conditional statements (#IFDEF VITIS_HLS etc.) that distinguish between Vitis HLS and Vivado HLS and only support Vivado HLS.

Parts of Coyote being affected
Mostly the HLS code and some SystemVerilog files. In some cases changes in the fpga-network-stack repository need to be made as well.