SAI IP Measurements (IPM) API proposal

[sperak-cisco]

Summary

This PR introduces IP Measurements (IPM) as a new SAI feature. It provides an API for configuring active measurement sessions and exposing delay, packet-count and path-health information.

Full design: doc/IPM/SAI-Proposal-IPM.md

Motivation

IPM was presented at SONiC workshop - OCP Global Summit 2024:
https://sonicworkshop2024ocp.sched.com/event/1kqSR/demo-ip-measurements-in-sonic-ahmed-abdelsalam-cisco

Changes

• Add SAI_API_IPM.
• Add SAI_OBJECT_TYPE_IPM_SESSION.
• Add SAI_OBJECT_TYPE_IPM_HISTOGRAM_PROFILE.
• Add saiipm.h with:
  • IPM session create, remove, set, and get operations.
  • Histogram-profile create, remove, set, and get operations.
  • Session statistics APIs.
  • Session-state and alternate-marking notifications.
• Add session configuration for:
  • Local and remote IP addresses and UDP ports.
  • Virtual router, DSCP, and IPv6 flow label.
  • Probe transmit interval and liveness timeout.
  • Plain IP/UDP or optional SRv6 encapsulation.
  • Optional reusable histogram profiles.
• Add statistics for:
  • TX and RX packet counts for alternate-marking values 0 and 1.
  • Per-bin receive delay histograms.
• Add switch attributes for:
  • Global alternate-marking interval.
  • IPM session enumeration.
  • Local UDP receive-port range.
  • Maximum supported histogram-bin count.
  • Notification callback registration.
• Extend metadata and Thrift handling for sai_u16_range_t.
• Add the IPM feature proposal, API examples, error handling and test plan.

Histogram profiles define immutable delay boundaries in nanoseconds. Boundaries must be positive, strictly increasing, and exactly representable. N boundaries define N + 1 bins.

The change is additive and leaves packet formats, timestamp representations and hardware mappings implementation-specific.

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[sperak-cisco]

564cd6b history-only rebase with no functional change.

[sperak-cisco]

e71dc8e history-only rebase with no functional change.