allow per-interface filtering for "show interfaces counters errors"

[donggyu-nexthop]

What I did

fixes #4501

Added per-interface filtering for the show interface counters suite of commands (for ones that didn't already have this feature)

How I did it

in interfaces/__init__.py, I updated counters sub-commands that didn't support per-interface filtering to take in an optional INTERFACE positional argument.

I added per-interface filtering support for the following commands:

• show interfaces counters errors
• show interfaces counters fec-stats
• show interfaces counters rates
• show interfaces counters was also updated to use a positional argument instead of the -i flag

This filtering functionality already existed for the other sub-commands. After discussions it was decided that it'd be best to keep the CLI consistent (with other CLI commands that provide per-interface filtering) by providing filtering capabilities via positional arguments rather than a flag.

How to verify it

on a DUT:

# display single-row table for Ethernet0
show interfaces counters Ethernet0

# display single-row errors table for Ethernet0
show interfaces counters errors Ethernet0

# display single-row table with tx/rx rates
show interfaces counters rates Ethernet0 

# display single-row table for FEC data
show interfaces counters fec-stats Ethernet0

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

Running show interfaces counters Ethernet0 would spit out a message saying something along the lines of "Ethernet0 is not a valid command".

Running show interfaces counters errors Ethernet0 would ignore the interface argument, and print out the counters table for all admin-up interfaces

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

$ show interfaces counters Ethernet0
    IFACE    STATE    RX_OK    RX_BPS    RX_UTIL    RX_ERR    RX_DRP    RX_OVR    TX_OK    TX_BPS    TX_UTIL    TX_ERR    TX_DRP    TX_OVR
---------  -------  -------  --------  ---------  --------  --------  --------  -------  --------  ---------  --------  --------  --------
Ethernet0        X        0  0.00 B/s      0.00%         0         0         0        0  0.00 B/s      0.00%         0         0         0

$ show interfaces counters errors Ethernet0
    IFACE    STATE    RX_ERR    RX_DRP    RX_OVR    TX_ERR    TX_DRP    TX_OVR
---------  -------  --------  --------  --------  --------  --------  --------
Ethernet0        X         0         0         0         0         0         0

$ show interfaces counters fec-stats Ethernet0
    IFACE    STATE    FEC_CORR    FEC_UNCORR    FEC_SYMBOL_ERR    FEC_PRE_BER    FEC_POST_BER    FEC_PRE_BER_MAX    FLR(O)    FLR(P) (Accuracy)    FEC_MAX_T
---------  -------  ----------  ------------  ----------------  -------------  --------------  -----------------  --------  -------------------  -----------
Ethernet0        X         N/A           N/A               N/A            N/A             N/A                N/A       N/A                  N/A          N/A

$ show interfaces counters rates Ethernet0
    IFACE    STATE    RX_OK    RX_BPS    RX_PPS    RX_UTIL    TX_OK    TX_BPS    TX_PPS    TX_UTIL
---------  -------  -------  --------  --------  ---------  -------  --------  --------  ---------
Ethernet0        X        0  0.00 B/s    0.00/s      0.00%        0  0.00 B/s    0.00/s      0.00%

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