Fix watermark bug2

[tingxin]

hot fix bug: the text was cut
root cause: the text width does not been calculate right due to some especial char
hot fix way: improve the calculate way to especial char

[wchaws]

@tingxin
svg "text-anchor" 可以让你避免计算文字宽度 https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/text-anchor

  <text text-anchor="start" x="60" y="40">A</text>
  <text text-anchor="middle" x="60" y="75">A</text>
  <text text-anchor="end" x="60" y="110">A</text>

高度方向用 baseline-shift 看这个例子：https://github.com/wchaws/sharp-text/blob/main/index.js

  <text
  x="0" y="500"
  fill="white"
  text-anchor="start"
  font-size="80px"
  baseline-shift="15%"
  font-family="Open Sans"
  >
  中 sw
  </text>

---

2022/10/17 updates

Sharp 增加了 text API lovell/sharp#512 (comment) 看上去这个方案可以完美解决我们的问题

参考链接：

• https://www.w3.org/TR/SVG/text.html#GlyphsMetrics
• https://observablehq.com/@julesblm/svg-dominant-baseline-alignment-baseline-attributes?collection=@julesblm/svg