Convert Gitlab::Graphql::Present to a field extension

What does this MR do?

In order to make our resolver tests play nicely with our instrumentation, I realised that the most sensible thing was to replace the instrumentation with field extensions. This has the additional benefit is that field extensions are the supported API for modifying field resolution. Significantly, field instrumentation is one of the proc-dependent features that are incompatible with the new interpreter (see: https://graphql-ruby.org/queries/interpreter.html#compatibility).

We intend to move to the interpreter (see: #210556 (closed) and !27536 (merged)) - and replacing the presenter instrumentation will be required.

This MR was split from !55306 (merged), where it was initially reviewed by @digitalmoksha.

Related to: #210556 (closed)

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