Extra timing on hot reload (#104242)

This PR adds extra timings for a hot reload.
As an example, before a user might see

> Performing hot reload...                                                
> Reloaded 1 of 788 libraries in 554ms.

With this PR it would instead be something like

> Performing hot reload...                                                
> Reloaded 1 of 788 libraries in 554ms (compile: 33 ms, reload: 153 ms, reassemble: 310 ms).