Move forms to sidepanel

表单组件迁移到 SidePanel
原 Popup 引导打开 SidePanel
优化表单组件和 Hooks，获取 Form 组件 Ref

assets/global.less

@@ -17,9 +17,11 @@ h2 {
 
 button {
   padding: 0;
+  width: 100%;
   border: none;
+  padding: .75em;
   cursor: pointer;
-  background-color: transparent;
+  border-radius: .5em;
 }
 
 img {
@@ -46,10 +48,6 @@ button, input, textarea {
   font: inherit;
 }
 
-form button {
-  background-color: #eee;
-}
-
 textarea {
   resize: vertical;
 }