* Added support for deserializing BgObject types directly into native classes.
* Removed opcodes for creating graph structures. These are now created in user code from BgObject types.
* Removed BgNodeSpecBuilder. BgNode objects can now be modified directly (returning a modified copy).
* Added concrete types for option parameters. The VM now keeps track of any parameters for evaluated options, allowing them to be added into the graph definition.
* Order dependencies now take nodes rather than outputs.
* Added explicit support for native thunks, whose bindings are saved to a sideband channel during compilation and referenced in bytecode as an index. This generalizes code that was previously specific to node definitions.
* Added a name table to bytecode, to optimize situations where we reference the same string mulitple times.
#preflight 62bf3c583f0d6beee2e8f4a6
[CL 20918762 by Ben Marsh in ue5-main branch]
* Expression classes (nodes, aggregates, graphs, etc...) are now called BgNode, BgAggregate, etc...
* Evaluated and instantiated objects used by BuildGraph internals are now called BgNodeDef, BgAggregateDef, etc...
#preflight 62b6374161016695a6545b08
[CL 20818158 by Ben Marsh in ue5-main branch]
