Allow HSV color initialization in `LightParameter` from YAML

[IanTheEngineer]

Currently, LightParameter's color attribute accepts Rgba YAML initialization only. Providing an HSV YAML spelling would enable useful things like sampling from Gaussian distributions over the HSV space when resolving stochastic color parameters for lighting.

This might take the form of something like the following using a YAML tag:

color: !Hsv
  hsv: [0.08333, 1.0, 1.0] #  orange

vs the current:

color: 
  rgba: [1.0, 0.5, 0.0] #  orange, with optional alpha

[jwnimmer-tri]

Assigning to +@zachfang for triage per https://drake.mit.edu/issues.html.

[jwnimmer-tri]

(From my perspective, this is low priority because teaching the domain-randomization tools to randomize in HSV and then convert to RGB when writing out to YAML is likely to be pretty easy.)