* Why I did it
Enable Test sai api on bfn container with a lightweight container(saiserver).
[SAI-PTF][mlnx]Enable saiserver test container on mlnx container
How I did it
enable saiserver container on mlnx platform.
add docker-saiserver-mlnx.mk for building saiserver container
in platform/barefoot/docker-saiserver-mlnx, add necessary files that needs in saiserver container
How to verify it
Signed-off-by: richardyu-ms <richard.yu@microsoft.com>
