[PERF] Share Liberally During Execution

[iamrecursion]

Description

Currently execution makes heavy use of cloning values when performing memory and storage modification operations in the virtual machine. As these values are always structurally identical, there is an opportunity for us to decrease memory usage and decrease time spent doing allocations by sharing these notes in the tree as well.

We also have a potential opportunity for some (albeit less) sharing in the tree structures during inference. Certain trees are stably typed, which means they do have exactly the same structure. These, too, can be shared.

Spec

• Work out the changes needed to share at runtime.
• Add support for sharing during the VM's execution.
• Change the conversion from RSV to TCSV to deep clone everything.
• Add support for sharing in the type checker.