`tracefrom` index - implement as native feature of `ibs` instead of tracer/hook

Hooks/Tracers - must be used for debugging/customizing.
They making execution slower.
Also it's hard to add tracer/hooks if already have one (must not have any by default).

So, let's add couple optional maps to `ibs` which will be enabled by `vmconfig`.

cc: @mh0lt @awskii @somnathb1