ExecutionInfo

Metadata related to query execution. Note that AST should be lazy so as not to be evaluated at runtime (which would happen with a by-value property since { ExecutionInfo(stuff, ast) } is spliced into a query-execution site). Additionally, there are performance overheads even splicing the finalized version of the AST into call sites of therun` functions. For this reason, this functionality is being used only in ProtoQuill and only when a trait extends the trait AstSplicing. In the future it might potentially be controlled by a compiler argument.