refactor: 增加样式文件

Author: ArgoZhang

src/components/BootstrapBlazor.FluentSystemIcon/wwwroot/css/all.min.css

@@ -0,0 +1,4 @@
+@import url('../fluentsystemicons-filled.css');
+@import url('../fluentsystemicons-light.css');
+@import url('../fluentsystemicons-regular.css');
+@import url('../fluentsystemicons-resizable.css');