Consider adding denoiser, or option to use SVS in clouds pass

[shotamatsuda]

With coarse ray marching steps, the output becomes very noisy due to the stochastic offset. Adding a denoiser may help, but I’m not sure how it impact performance. Alternatively, SVS in the clouds pass may be worth revisiting to see if it performs well for certain cloud conditions, though it wil require adjustments to work with the growth factor.