Add fabric capacity monitoring code.

[jfeng-arista]

What I did
Add fabric capacity monitoring code.

The HLD can be found at
https://github.com/sonic-net/SONiC/blob/master/doc/voq/fabric.md

The current design does not cover the card hotswap/OIR cases. We will discuss how to handle that in a separate proposal.
Why I did it

How I verified it

Details if related

[jfeng-arista]

need #3089 merged to build

[arlakshm]

changes look good. Can we add UT for this?

[jfeng-arista]

changes look good. Can we add UT for this?

added

[jfeng-arista]

I checked failures, and they are not Fabric related tests, let me restart the test pipeline

[jfeng-arista]

/Azp run Azure.sonic-swss

[azure-pipelines]

Commenter does not have sufficient privileges for PR 3097 in repo sonic-net/sonic-swss

[jfeng-arista]

/azpw run Azure.sonic-swss

[mssonicbld]

/AzurePipelines run Azure.sonic-swss

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[jfeng-arista]

the failed tests not related to fabric

[jfeng-arista]

/azpw run Azure.sonic-swss

[mssonicbld]

/AzurePipelines run Azure.sonic-swss

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[jfeng-arista]

2024-04-25T22:45:55.3666646Z test_mux.py::TestMuxTunnel::test_acl FAILED [ 25%]
2024-04-25T22:46:38.3148266Z test_sub_port_intf.py::TestSubPortIntf::test_sub_port_intf_appl_db_proc_seq FAILED [ 50%]
2024-04-25T22:47:11.7348687Z test_mux.py::TestMuxTunnel::test_neighbor_miss[standby->ping_serv->active->resolve_entry->delete_entry-IPv6] FAILED [ 75%]
2024-04-25T22:49:30.8390555Z test_vnet.py::TestVnetOrch::test_vnet_orch_2 FAILED [ 25%]
2024-04-25T22:50:12.9072929Z test_twamp.py::TestTwampLight::test_SenderContinuousMulti FAILED [ 50%]
2024-04-25T22:50:46.0160473Z test_srv6.py::TestSrv6::test_srv6 FAILED [ 75%]
2024-04-25T22:51:39.4822773Z test_srv6.py::TestSrv6Mysid::test_mysid FAILED [ 80%]
2024-04-25T22:52:40.1379025Z test_srv6.py::TestSrv6::test_srv6 FAILED [ 90%]

above are the failed tests, looks like not related to this change

[arlakshm]

/Azp run Azure.sonic-swss

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).