Improve _apply(apply_type, ::Tuple, ::SimpleVector)
This is another one of those patterns that doesn't generally
come up except in Cassette/Zygote code. There's two related
changes here:
1. Expand ininling's _apply rewrite to also handle constant
svecs (under the restriction that they must be no longer than
the splatting cutoff and the elements must be individually eligible
for inlining into the IR)
2. Move the _apply rewrite before the special case inliner for builtins
such that _apply(apply_type, ...) gets eliminated early.
