usertools/telemetry: provide info on available sockets
usertools/telemetry: provide info on available sockets

When a user runs the dpdk-telemetry script and fails to connect because
the socket path does not exist, run a scan for possible sockets that
could be connected to and inform the user of the command needed to
connect to those.

For example:

  $ ./dpdk-telemetry.py -i4
  Connecting to /run/user/1000/dpdk/rte/dpdk_telemetry.v2:4
  Error connecting to /run/user/1000/dpdk/rte/dpdk_telemetry.v2:4

  Other DPDK telemetry sockets found:
  - dpdk_telemetry.v2  # Connect with './dpdk-telemetry.py'
  - dpdk_telemetry.v2:2  # Connect with './dpdk-telemetry.py -i 2'
  - dpdk_telemetry.v2:1  # Connect with './dpdk-telemetry.py -i 1'

Signed-off-by: Bruce Richardson <66b9e8e8fbd5e9f41f91b0af050876182ce9d0e4@intel.com>
Acked-by: Ciara Power <2dd8f648091a527a3f34edd30b226be01da76a0e@intel.com>
Reviewed-by: Conor Walsh <e53367a822c9a2a32150eba4386d4e8c8c837c8e@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk