Fix length properties on array methods (#1983)

This Pull Request fixes length properties on multiple array prototype methods that were including rest parameters in the count. More tests should pass.

It changes the following:

- Length properties on some array prototype methods

boa_engine/src/builtins/array/mod.rs

@@ -112,14 +112,14 @@ impl BuiltIn for Array {
         .method(Self::flat, "flat", 0)
         .method(Self::flat_map, "flatMap", 1)
         .method(Self::slice, "slice", 2)
-        .method(Self::some, "some", 2)
+        .method(Self::some, "some", 1)
         .method(Self::sort, "sort", 1)
-        .method(Self::splice, "splice", 3)
+        .method(Self::splice, "splice", 2)
-        .method(Self::reduce, "reduce", 2)
+        .method(Self::reduce, "reduce", 1)
-        .method(Self::reduce_right, "reduceRight", 2)
+        .method(Self::reduce_right, "reduceRight", 1)
         .method(Self::keys, "keys", 0)
         .method(Self::entries, "entries", 0)
-        .method(Self::copy_within, "copyWithin", 3)
+        .method(Self::copy_within, "copyWithin", 2)
         // Static Methods
         .static_method(Self::from, "from", 1)
         .static_method(Self::is_array, "isArray", 1)