Hex with alpha in URL causes Numberscope to complain

[katestange]

1. Go to http://localhost:5173/?name=Turtle&viz=Turtle&bgColor=7C4545&seq=Formula
2. Change background colour.
3. The URL now has the new bgColor in it, which is 8 characters long (including alpha)
4. URL reload causes errors in the parameters pane

[gwhitney]

I believe the issue is that the function isColor in ParamType.ts is too restrictive -- I think it insists on the # which I think the new picker does not always include (and which I am fine having be optional) and it definitely only allows 4 hex digits, when I think any of 3,4,6, or 8 are fine.

This is a small enough point that I think it can be folded into pretty much any PR for convenience's sake. Anyone who's about to do so should assign this issue to themselves.

[gwhitney]

Resolved with merge of #542 into ui2.