[Schema Inaccuracy] Many duplicated properties definitions in webhooks

[wolfy1339]

Schema Inaccuracy

There are many webhooks schemas where properties that represent a user are not using a common schema, ie simple-user or user, and are instead defining them by hand.

There is also the same issue with properties representing GitHub apps, they are redefining the "app" and not using the integration component

There are probably many more in the OpenAPI spec, however these are the ones i've seen.

Expected

For the webhooks schemas to not redefine user, app or other properties all the time and to use the appropriate common schema

Reproduction Steps

N/A