Automatic merge from submit-queue

Validate list objects when building scheme

The first commit is #29468. This PR is a followup.

Modified the description of **List** in api-convention.md to:
`The name of a list kind must end with "List". Lists have a limited set of common metadata. All lists use the required "items" field to contain the array of objects they return. Any kind that has the "items" field must be a list kind.`

Also added code to enforce the above rules during scheme registration.

@kubernetes/sig-api-machinery @bgrant0607 @erictune @lavalamp @smarterclayton