Improve Stack and HStack components

app/soapbox/components/ui/hstack/hstack.tsx

@@ -6,6 +6,7 @@ const justifyContentOptions = {
   center: 'justify-center',
   start: 'justify-start',
   end: 'justify-end',
+  around: 'justify-around',
 };
 
 const alignItemsOptions = {
@@ -32,7 +33,7 @@ interface IHStack {
   /** Extra class names on the <div> element. */
   className?: string,
   /** Horizontal alignment of children. */
-  justifyContent?: 'between' | 'center' | 'start' | 'end',
+  justifyContent?: 'between' | 'center' | 'start' | 'end' | 'around',
   /** Size of the gap between elements. */
   space?: 0.5 | 1 | 1.5 | 2 | 3 | 4 | 6 | 8,
   /** Whether to let the flexbox grow. */

app/soapbox/components/ui/stack/stack.tsx

@@ -4,6 +4,7 @@ import React from 'react';
 type SIZES = 0 | 0.5 | 1 | 1.5 | 2 | 3 | 4 | 5 | 10
 
 const spaces = {
+  0: 'space-y-0',
   '0.5': 'space-y-0.5',
   1: 'space-y-1',
   '1.5': 'space-y-1.5',