Use bazel to compile sai_p4 program

[daniele-moro]

The pipeliner for sai_p4 requires:

• the P4Info file
• the bmv2 JSON configuration file (this is probably not needed, but it's required for now)

Currently, we use a Docker container (opennetworking/p4c:stable-20210108) to build the P4 program via some make targets.
We should use bazel as in the pins-infra repo to build the program to have consistent builds and P4Info files.