Improve displaying values of getters

[thetarnav]

#107 added support for component props, but only the static props have their values displayed. This is because we don't want the debugger to read the getters, those—if not memorized—will over execute their function. This is mainly important for passing JSX as props—executing them will create dom nodes every time.

There needs to be a way to solve it though. Seeing the values of getters could be very important in some cases.
Preact devtools showed that they can do it. Their signal API design puts them at an advantage here, but to some degree, the same patterns could be implemented here.

The key to the solution might be a way to proxy the props object before providing it as a function argument and intercept property reads, saving and displaying the last read value.
This way we would display without executing them outself.
The problems here are stale values. getter not yet read won't have it's value, and getter that is not currently "subscribed to" by the user, might be stale. Showing those values to the user without any indication of possibly stale values could be misleading.
Using getListener() while intercepting the read might be useful here.