[Feature] Add CLI support for configuring persistent drop monitor

[arista-hpandya]

Description:

This issue tracks the implementation of CLI support for configuring and managing the persistent drop monitor feature in SONiC. This feature enables users to define thresholds for drop counts and incident counts within a specified time window, which triggers syslog entries when persistent drops are detected.

Tasks:

• Implement new CLI commands to enable/disable and configure the persistent drop monitor, including:
  • Setting the monitoring window size (-w/--window)
  • Setting the drop count threshold (-dct/--drop-count-threshold)
  • Setting the incident count threshold (-ict/--incident-count-threshold)
• Update the show dropcounters monitor command to display the current monitor configuration.
• Implement input validation and error handling for the new CLI commands.
• Add unit tests to cover the new CLI functionality.
• Update documentation to reflect the new CLI commands and options.

Background:

The persistent drop monitor feature allows for proactive monitoring and identification of persistent packet drops in the SONiC environment. It builds upon the existing drop counter functionality and provides a mechanism to detect and log sustained drop patterns. The configuration is global and applies to all configured drop counters on the device.

References:

• Related HLD document: HLD document for configurable drop counter monitoring SONiC#1912
• Master issue tracking overall progress: Internal drop counter monitoring SONiC#1542

Assignee:
@arista-hpandya