Include core instance sizes in component_instance_size limit

[posborne]

There exist several knobs for limiting the memory that might be consumed for metadata for components. For core module instances within a component, the two that previously existed to control metadata allocations have been:

• A: max_core_instances_per_component
• B: component_instance_size

These allow for an embedder to set an upper bound on memory used by a component's instances to A * B. This value could be quite large for some systems and it would be nice to be able to set a cap on the total memory that might be used for metadata across all instances while still allowing for a greater number of instances with the potential for a subset of those instances to be relatively large.

To allow for aggregate control over memory used within the runtime for componenets, the existing max_component_instance_size limit is extended to consider both the VMComponentCtx size as well as the aggregate size of all core instances in the component.

The original changeset which introduced a separate config knob was #12768 which this replaces.

[github-actions]

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[alexcrichton]

Thanks!