Specify syntax for component YAML and input parameters

What does this MR do and why?

Related to #377327 (closed)

In this MR we introduce the syntax of the component yaml file and more specifically focus on spec:inputs for components but also other include: types.

NOTE: the filename and path of the "component yaml" is currently being re-discussed in Define CI components syntax (#377327 - closed). In this MR we focus discussions on the spec:inputs primarily.

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