feat(web): use bg replace img

web/src/assets/images/common/return.svg

@@ -1,17 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg width="16px" height="16px" viewBox="0 0 16 16" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
-    <title>退出</title>
-    <g id="空间里层页面优化" stroke="none" stroke-width="1" fill="none" fill-rule="evenodd" stroke-linecap="round" stroke-linejoin="round">
-        <g id="记忆库-个人记忆-遗忘记忆" transform="translate(-1357, -24)" stroke="#171719">
-            <g id="返回空间" transform="translate(1349, 16)">
-                <g id="退出" transform="translate(16, 16) scale(-1, 1) translate(-16, -16)translate(8, 8)">
-                    <g id="编组-7" transform="translate(3.5, 2.5)">
-                        <path d="M3.47826087,11 L1.8,11 C0.80588745,11 0,10.1941125 0,9.2 L0,1.8 C-2.22044605e-16,0.80588745 0.80588745,-2.22044605e-16 1.8,-4.4408921e-16 L3.47826087,0 L3.47826087,0" id="路径"></path>
-                        <line x1="9.56521739" y1="5.5" x2="2.60869565" y2="5.5" id="路径-6"></line>
-                        <polyline id="路径" points="7.82608696 3.20833333 10 5.5 7.82608696 7.79166667"></polyline>
-                    </g>
-                </g>
-            </g>
-        </g>
-    </g>
-</svg>