Mixin to include segmentOwner and FeedName for external segmentdefinition schema

[knarayanan88]

Add a new mixin to include the segmentOwner and FeedName of external segment definitions. The mixin intendsToExtend the segmentdefinition standard class.

What are the schemas that are affected by the issue

• None;

What are examples of products that are impacted by the issue

• 2P Audience Sharing - A new initiative by AEP.