sonic-swss: Code changes for WRED and ECN statistics

[rpmarvell]

• New flex counter group for per-Queue WRED and ECN statistics

• New flex counter group for per-Port WRED and ECN statistics

  Signed-off-by: [email protected]

What I did WRED and ECN statistics support

Why I did it Implemented as per the HLD : https://github.com/sonic-net/SONiC/blob/ebcd2a4a987f1d6027cd57677dc6806b8a9adcdb/doc/qos/ECN_and_WRED_statistics_HLD.md

How I verified it Verfied it using Marvell DUT and SWSS unit tests.

Details if related

• Two new flex counters added for per-Queue and per-Port WRED ECN statistics.

Build dependency on sonic-swss-common pull request : https://github.com/sonic-net/sonic-swss-common/pull/777

Expected order of dependent pull-request to be committed :

1. sonic-swss common pull request : https://github.com/sonic-net/sonic-swss-common/pull/777
2. sonic-sairedis pull request : https://github.com/sonic-net/sonic-sairedis/pull/1234
3. sonic-swss : pull request : https://github.com/sonic-net/sonic-swss/pull/2750
4. sonic-yang-model pull requests : https://github.com/sonic-net/sonic-buildimage/pull/14758
5. sonic-utilities pull request : https://github.com/sonic-net/sonic-utilities/pull/2807