Add Infiniband support for reading and exposing counters and stats

[vakalapa]

Is your feature request related to a problem? Please describe.
Add support to read Infiniband ports counters and stats from mlnx drivers.

https://enterprise-support.nvidia.com/s/article/understanding-mlx5-linux-counters-and-status-parameters

We can extend linux util plugin to start reading Linux port counters and status parameters located under /sys/class/infiniband/ and /sys/class/net locations, and expose them as metrics.

Ideally we should introduce a new plugin to read and convert these metrics.

Some references:
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/configuring_infiniband_and_rdma_networks/understanding-infiniband-and-rdma_configuring-infiniband-and-rdma-networks
https://enterprise-support.nvidia.com/s/article/understanding-mlx5-linux-counters-and-status-parameters