List - varargs for Append, NewList, Prepend

[laher]

Would it be desirable to amend the signatures for these List operations?

e.g.

func (l *List[T]) Append(value ...T) *List[T] {

2 benefits:

• Ergonomics: no need for ListBuilder in many cases
• Efficiently add multiple to an existing List

Being varargs, it wouldn't break existing callers.

Note that we could implement something similar for maps - maybe a SetAll(map[k]v) but that could be separate.

I'm happy to submit a PR for this

[laher]

Duh, I missed this: #18.

I could implement it under that one