[Malleability Immutable] Enforce immutability for MissingCollection

This issue tracks enforcement of immutability for the MissingCollection type as part of #7269.

Goals

• Introduce a *Builder type or constructor for MissingCollection, used while the object is being constructed
• Eliminate all mutable operations on MissingCollection instances
• Enable the malleability linter for this type (see #7270)
• Implement ID caching where appropriate
• Remove legacy/duplicated ID caching behavior

Checklist

• Add a *Builder or constructor for MissingCollection
• Remove all remaining mutations
• Enable linter for MissingCollection
• Implement and use cached ID accessor
• Remove any old code paths caching the ID

Related: #7269