[thresholdorch] Threshold feature

[PrabhuSreenivasan]

Signed-off-by: Prabhu Sreenivasan [email protected]

Threshold feature changes extracted from https://github.com/Azure/sonic-swss/pull/1067

What I did Add support for threshold feature which allows user to set threshold on packet buffer utilization and record threshold breaches.

Why I did it Helps track packet buffer utilization going beyond the user configured values.

How I verified it pytest scripts included.

Details if related

Dependent PRs https://github.com/Azure/sonic-swss/pull/1525 https://github.com/Azure/sonic-swss-common/pull/433

Related PRs https://github.com/Azure/sonic-swss-common/pull/433 https://github.com/Azure/sonic-tam/pull/13 https://github.com/Azure/sonic-buildimage/pull/6222 https://github.com/Azure/sonic-utilities/pull/1313