Add new utils for wrapping & flattening arrays.

packages/field-kit/src/utils/asArray.js

@@ -1,4 +1,18 @@
 // Wrap a value in an array, unless it's nullish, then return an empty array.
 const asArray = value => (value ? [value] : []);
 
+// Like above, but checks if the value is already an array and if so returns it as is.
+export const asFlatArray = value => (Array.isArray(value) ? value : asArray(value));
+
+// Like asFlatArray() or Array.from(), but with a few more differences: unlike
+// asFlatArray(), it will always return a shallow copy and will handle iterable
+// objects as well; and unlike Array.from(), it will return the empty array for
+// nullish values instead of throwing an exception, while all other non-nullish,
+// non-iterable values will be returned wrapped in a new array.
+export const fromFlatArray = value => (
+  typeof value[Symbol.iterator] === 'function'
+    ? Array.from(value)
+    : (value ? [value] : [])
+).flat(Infinity);
+
 export default asArray;