Make implementation more scalable by using a helper trait to determine bitmask size. Improve bitmask to int conversion.

crates/test_helpers/src/array.rs

@@ -3,14 +3,11 @@
 // Adapted from proptest's array code
 // Copyright 2017 Jason Lingle
 
+use core::{marker::PhantomData, mem::MaybeUninit};
 use proptest::{
     strategy::{NewTree, Strategy, ValueTree},
     test_runner::TestRunner,
 };
-use core::{
-    marker::PhantomData,
-    mem::MaybeUninit,
-};
 
 #[must_use = "strategies do nothing unless used"]
 #[derive(Clone, Copy, Debug)]