Unroll (list ...) constructs to List ctor calls

For small (list arg1 arg2 arg3) constructs, have the macro expand to code that directly uses the List ctor.

Here is an example of the perf benefit in the case of 2 arguments:

produces

While

produces

Perhaps this could be done for any number of list arguments, or, if perf becomes an issue for large numbers of arguments maybe it could be done only up to a certain size. (Maybe CLJS-910 factors in on older JavaScriptCore instances.)

CLJS-1617 is relevant.