Add helpers for fetching ConfigDB entries on multi-asic

[bktsim-arista]

Why I did it

This change adds generic functions that can be used to fetch tables from ConfigDB for multi-asic devices based on previous functions created for fetching PORT tables. These functions are to be used in upcoming changes for adding multi-asic support for show/config commands for #15148 to prevent duplicate code.

How I did it

Modified previously existing helper functions for fetching ports in multi-asic devices and made then generic.

Description for the changelog

Added generic helper functions for fetching ConfigDB entries for multi-asic devices.

[kenneth-arista]

@vmittal-msft @arlakshm please review

[vmittal-msft]

@yxieca @wangxin please help merge

[yxieca]

@yxieca @wangxin please help merge

@vmittal-msft have you test this change against single asic / T0 / T1 boxes?

[arlakshm]

@yxieca @wangxin please help merge

@vmittal-msft have you test this change against single asic / T0 / T1 boxes?

@yxieca these changes are not needed for 202205 or 202305. These changes will go in 202405, Please help merge the changes in master

[yxieca]

@yxieca @wangxin please help merge

@vmittal-msft have you test this change against single asic / T0 / T1 boxes?

@yxieca these changes are not needed for 202205 or 202305. These changes will go in 202405, Please help merge the changes in master

@vmittal-msft @arlakshm this question is irrelevant with back porting, I just want to know if this change is single-asic safe?

[rlhui]

@bktsim-arista please also help confirm if this is tested for single-asic, thanks

[kenneth-arista]

@yxieca and @rlhui I can confirm that these changes have been tested on single ASIC platforms against the master branch. Specifically, multi_asic.get_port_table() is used implementing show interfaces alias (see https://github.com/sonic-net/sonic-utilities/blob/master/show/interfaces/__init__.py#L67). We have executed sonic-mgmt/test_iface_namingmode.py tests against m0, t0, and t1 topologies successfully with these changes.

[bingwang-ms]

@bktsim-arista Please raise a PR to 202405 to address conflict.