Autogenerate tagging-compliant descriptor methods for all archetypes

[teh-cmc]

Generate methods for all archetypes that allow retrieving the fully-qualified descriptor for any of the archetype's field.
E.g. this method returns the descriptor for the radii field of Points3D:

impl Points3D {
    /// Returns the [`ComponentDescriptor`] for [`Self::radii`].
    #[inline]
    pub fn descriptor_radii() -> ComponentDescriptor {
        ComponentDescriptor {
            archetype_name: Some("rerun.archetypes.Points3D".into()),
            component_name: "rerun.components.Radius".into(),
            archetype_field_name: Some("radii".into()),
        }
    }
}

This becomes a must as we start require tags in more and more places (e.g. partial updates APIs).

• DNM: requires New types and traits for (co-existing!) eager serialization #8642
• Part of New partial updates logging APIs: Rust #8581

[github-actions]

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Result	Commit	Link	Manifest
✅	404b22f	https://rerun.io/viewer/pr/8643	+nightly +main

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