Fix multi-asic behaviour for queuestat

[arista-hpandya]

What I did

• Added support for iterating over all namespaces (ns) when none specified
• Added a test case to verify all ns behaviour
• Introduced a wrapper class to handle the mutli-asic functionality
• Replaced argparse with click for better argument checks

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

How I did it

Modified the queuestat script and associated test files.

How to verify it

The changes were verified by:

• Running all the unit tests in conic-utilities
• Verifying the changes manually on a T2 single-asic linecard
• Verifying the changes manually on a multi-asic linecard

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

Cmd: queuestat
Result: Empty

Reason: When the namespace (-n/--namespace) argument is not specified on a multi asic device the scripts will return nothing.

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

Cmd: queuestat
Result: Runs on all asics present on the device.

Reason: To be consistent with the other PRs in #15148, we iterate over all namespaces when none is specified on a multi-asic device.

Test snapshots provided below:

Specifying invalid namespace on single asic devices: queuestat -n asic0

Single asic behaviour is preserved: queuestat -p Ethernet152

Multi asic behaviour when namespace is specified: queuestat -n asic1 -p Ethernet-Rec1

Multi asic behaviour when no namespace is specified: queuestat

.
.
.

.
.
.

[kenneth-arista]

@wenyiz2021 @arlakshm @vmittal-msft

[wenyiz2021]

result LGTM, haven't check code details