* Rename the 'Identity' node to 'Passthrough' internally
* Rename the 'Memoize' node to 'Cache' internally
* Let skip_impl proto nodes auto-generate as document node definitions
* Remove the wrapper 'Passthrough' node from document_node_definitions.rs
* Remove the wrapper 'Cache' node from document_node_definitions.rs
* Remove the wrapper 'Monitor' node from document_node_definitions.rs
* Remove the wrapper 'Noise Pattern' node from document_node_definitions.rs
* Remove the wrapper 'Brush' node from document_node_definitions.rs
* Remove the wrapper 'Transform' node from document_node_definitions.rs
* Code review improvements
* Rename Cache node back to Memoize
* More code review
* Feature-gate serde derives behind cfg_attr in all runtime node graph type crates
* Refactor Table to move its hard-coded fields into an attributes field
* Encapsulate TableRow/TableRowRef/TableRowMut attribute fields behind accessor methods
* Remove TaggedValue::GraphicUnused
* Refactor Table<T> to use dynamic attributes instead fixed names
* Fix code review soundness concerns
* Add todo work
* Replace row-oriented Table<T> API with column-oriented access
* Fix attribute propagation bugs
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