Incorrect indentation alignment in markdown parser

[hexh250786313]

Describe the bug

I found that the markdown parser in coc causes incorrect hierarchical alignment in markdown lists.

I added the following debugging code to retrieve the source markdown text and the parsed text:

// coc.nvim/src/markdown/index.ts line:168
  ...
  let startLnum = 0
  console.log('---source', content)
  let parsed = marked(content)
  console.log('---parsed', parsed)
  let links = Renderer.getLinks()
  ...

Here are the comparisons of source, coc parsed, markdown-preview-enhanced and github parsed:

You can see that the one parsed by coc results in incorrect indentation alignment, causing the entire section of the list item to have an extra two spaces of indentation to the right.

[hexh250786313]

https://github.com/neoclide/coc.nvim/pull/4884 may help