Implements ButtonGroup component

packages/bbui/src/ButtonGroup/ButtonGroup.svelte

@@ -0,0 +1,7 @@
+<script>
+    export let vertical = false
+</script>
+
+<div class="spectrum-ButtonGroup" class:spectrum-ButtonGroup--vertical={vertical}>
+    <slot />
+</div>

packages/bbui/src/index.js

@@ -15,6 +15,7 @@ export { default as ActionButton } from "./ActionButton/ActionButton.svelte"
 export { default as ActionGroup } from "./ActionGroup/ActionGroup.svelte"
 export { default as ActionMenu } from "./ActionMenu/ActionMenu.svelte"
 export { default as Button } from "./Button/Button.svelte"
+export { default as ButtonGroup } from "./ButtonGroup/ButtonGroup.svelte"
 export { default as ClearButton } from "./ClearButton/ClearButton.svelte"
 export { default as Icon, directions } from "./Icon/Icon.svelte"
 export { default as Toggle } from "./Form/Toggle.svelte"