Make Stratum-bfrt QoS configurable with singleton port IDs

[pudelkoM]

This PR add the option to use SingletonPort IDs instead of sdk ports in the QoS config for Tofino.

TODO:

• test on HW

[codecov]

Codecov Report

Merging #808 (7e0e6f6) into main (3bcaec5) will decrease coverage by 0.03%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #808      +/-   ##
==========================================
- Coverage   78.63%   78.60%   -0.04%     
==========================================
  Files         334      334              
  Lines       30006    30019      +13     
==========================================
  Hits        23595    23595              
- Misses       6411     6424      +13     

Impacted Files	Coverage Δ
stratum/hal/lib/barefoot/bf_chassis_manager.cc	72.65% <0.00%> (-1.04%)	⬇️

[pudelkoM]

The latest commit is an experiment with adding a common TofinoPort. Has the drawback that the oneof does not directly embed in the parent message anymore, thus needing an extra port { sdk_port: 1 } wrapper in the text config.

[ccascone]

The proto changes look good to me

[pudelkoM]

The common tofino port message did not really save any code once I found a way to shorten the namespace for the port type case, so I reverted it back to direct embed, which makes the config itself easier to read and write.