update build to webpack v5 + add typescript definition file along with build changes

Author: rob2d

build/index.d.ts

@@ -0,0 +1,14 @@
+/**
+ * Hook which observes viewport dimensions.
+ *
+ * If input not specified, returns the [width, height] when the window changes.
+ * If input is specified as a number, it returns the [width, height].
+ *
+ * If the input is specified as a function, it accepts a callback
+ * with the viewport width and height passed in the first arg as
+ * { vpW, vpH }, and will only return a new value and update when
+ * the hash-value returned changes.
+ */
+export declare function useViewportSizes(
+    input:number | (({ vpW: number, vpH: number }) => String)
+):[vpW: number, vpH: number];