Add support for translating multiple tag attributes

[dannycolin]

Before submitting a bug report

• I updated to the latest version of Multi-Account Container and tested if I can reproduce the issue
• I searched for existing reports to see if it hasn't already been reported

Step to reproduce

N/A

Actual behavior

The current code in js/i18n.js doesn't let us specify an attribute.

Expected behavior

We should be able to translate attributes. Code example:

  document.querySelectorAll('[data-i18n]').forEach(node => {
    let [attr, text] = node.dataset.i18n.split('|');
    text = browser.i18n.getMessage(text);
    attr ? node.setAttribute(attr, text) : node.append(text);
  });
  <input data-i18n="placeholder|Here the text for my placeholder">

To support multiple attributes, we simply split the string twice and use two different delimiter. For example,

<input data-i18n="placeholder:My Placeholder|title:My Title">

Additional informations

No response

Provide a copy of Troubleshooting Information page

N/A