Add a design system (#34)

* Add theming system

* Add standard Button control and update RadioButtons

* Unify radiobutton with design system

* Update debug screen to have multiple views

* Add ToggleButton

* Update error controls to use design system

* Add typography to <Text> element

* Move DropdownButton into the design system

* Clean out old code

* Move Text into design system

* Add 'inverted' color palette

* Move LoadingPlaceholder into the design system

src/view/lib/hooks/useAnimatedValue.ts

@@ -0,0 +1,12 @@
+import * as React from 'react'
+import {Animated} from 'react-native'
+
+export function useAnimatedValue(initialValue: number) {
+  const lazyRef = React.useRef<Animated.Value>()
+
+  if (lazyRef.current === undefined) {
+    lazyRef.current = new Animated.Value(initialValue)
+  }
+
+  return lazyRef.current as Animated.Value
+}