[Cherry pick][202405] Add multi asic support for dropconfig

[arista-hpandya]

What I did

• Added support for iterating over all namespaces (ns) when none specified
• Added a test cases to verify multi-asic behaviour
• Introduced a wrapper class to handle the mutli-asic functionality

This script was missed during the initial efforts to add multi-asic support.

How I did it

This is in accordance to the issue sonic-net/sonic-buildimage#15148 which tracks the multi-asic support for scripts in sonic-utilities.

How to verify it

The changes were verified by:

Running all the unit tests in sonic-utilities
Verifying the changes manually on a single-asic linecards
Verifying the changes manually on a multi-asic linecards

Screenshots of the manual tests:

Running on all namespaces when none specified

---

Running commands on specific namespaces

---

When an invalid namespace name is passed

Tests on ToR device

Previous command output (if the output of a command-line utility has changed)

Single asic command outputs remain untouched

New command output (if the output of a command-line utility has changed)

New multi asic command outputs will start with the prefix: `For namespace: "

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).