parse doca-pipe-group and compute total mask/pipe per group

[nick-bouliane]

Add DOCA pipe group entry metrics

This PR adds metrics to track the number of entries in each DOCA pipe group.

Changes

Added 8 new gauge metrics:

• ovsdp_doca_pipegroup_main_entries - Main table (group_id=0x00000000)
• ovsdp_doca_pipegroup_sample_postmirror_entries - Sample-post-mirror table (0xf2000000)
• ovsdp_doca_pipegroup_split_postprefix_entries - Split-post-prefix table (0xfa000000)
• ovsdp_doca_pipegroup_posthash_entries - Post-hash table (0xfb000000)
• ovsdp_doca_pipegroup_postct_entries - Post-CT table (0xfd000000)
• ovsdp_doca_pipegroup_postmeter_entries - Post-meter table (0xff000000)
• ovsdp_doca_pipegroup_ct_entries - Aggregated CT entries across all zones (0xfc0*)
• ovsdp_doca_pipegroup_ctnat_entries - Aggregated CT-NAT entries across all zones (0xfc1*)

Implementation

• Parses output from ovs-appctl doca-pipe-group/dump
• Counts entries by matching lines starting with esw= and extracting group_id
• Uses exact matching for infrastructure tables and prefix matching for dynamic CT/CTNAT zones
• Returns -1 on error, following existing metric conventions

[ChachiTheGhost]

@nick-bouliane has this been tested in a container on a DPU?