Support variable number of arguments idomatically via `params T[]`

[decaprime]

Support using params in last parameter to capture a typed array of the remaining parameters.

There's two approaches for this with VCF, capturing as params string[] for all arguments and letting commands handle or capturing as a VCF supported type. The second approach is more natural one for VCF, albeit more surface area.

Consider:

[Command("make team")]
void MakeTeam(ICommandContext ctx, string teamName, params Player[])

This signature would support using some Player converter, and try to convert all the parameters before invoking the method.

.make team "Just For Fun" Kelly Kevin Meredith Erin

Though honestly that was a pain to type just for this example, I wanted to put commas in the list.