don't restart rendering when changing noise level

When viewport rendering to find the best noise level for the final render, you often find that the noise level was inadequate so you need to lower it a bit. The problem is that Blender will restart the render from the beginning, leading to unnecessary waiting times.

I'd suggest either or Both of the below:

A) Resume rendering rather than restarting when user changes noise level.

B) User sets the noise level extremely low so that it will render until manually stopped. Then show the current (lowest) noise level of the pixels that have not yet met the noise level requirements. This could be shown as a toggleable heat map (lowest incomplete to highest noise levels) + text info overlay next to the sample in the top left.