Improve in-editor display

Currently, timings/number of ticks are displayed as code lenses:

Imho, this is slightly annoying because a) it moves your code around and b) it's hard to get a quick overview over which line in your code is expensive to execute.
I'd like to propose an alternative display mode that instead changes the line background color up to a width proportional to the amount of time spent on that line relative to the current frame's total time (Juno has that feature):

Ignore the drastically different results for now, I think our Julia -> .cpuprofile translation has a bug somewhere.

This is possible with the current decoration API, but might require padding the end of the line with spaces.