First Class Deprecations for GraphQL

What does this MR do?

This MR makes deprecation information a first class property of GraphQL types (fields, arguments and enum members). Rather than affecting the description and otherwise being erased, deprecation information is preserved and stored on the deprecated element, so it can be retrieved later.

This enables better handling in the generated GraphQL docs. Other work builds on this. See !55944 (merged) and !56704 (merged)

Screenshots (strongly suggested)

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