[202311][WCMP]: Add W-ECMP to BGP OA

[nazariig]

Signed-off-by: Nazarii Hnydyn nazariig@nvidia.com

HLD: sonic-net/SONiC#1629

Why I did it

• W-ECMP feature implementation is according to the HLD

Work item tracking

• N/A

How I did it

• Added W-ECMP YANG model implementation
• Added W-ECMP BGP OA implementation

How to verify it

1. Run UTs
2. Verified manually with the feature qualification

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111
• 202205
• 202211
• 202305
• 202311

Tested branch (Please provide the tested image version)

• 202311

Details if related

• Backport from master: Add W-ECMP to BGP OA #18533

Description for the changelog

• N/A

Link to config_db schema for YANG module changes

• N/A

A picture of a cute animal (not mandatory but encouraged)

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[nazariig]

/azpw run Azure.sonic-buildimage

[mssonicbld]

/AzurePipelines run Azure.sonic-buildimage

[azure-pipelines]

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