Instrument all functions

[sliminality]

Rather than instrumenting only exported functions, we should instrument all functions in the function index space (including the standard library) except for the transitive closure of functions invoked by the Tracer.

• Compute callgraph
• Instrument all functions except those transitively invoked by our functions

[fitzgen]

Another potential approach: For functions that are called by both wasm-trace's runtime and the users code (eg if the user used VecDeque right now too) we could also have a flag in the runtime that is always set if we are currently logging an event, and unset if we are not. This could protect against re-entry and still allow shared functions to be instrumented.