Backport #40053 by @silverwind
Copying lines from a diff, file view, blame, code search or code preview
and pasting them into a comment on Gitea or GitHub produced a markdown
table with escaped pipes and stripped indentation. Both use
`@github/paste-markdown`, which converts copied HTML tables unless they
carry `data-paste-markdown-skip`, as GitHub's own code tables do.
Gitea's code tables now set it too.
The test is a bit more complicated because of a upstream bug which
causes `paste-markdown` to insert pasted content twice, once
https://github.com/github/paste-markdown/pull/128 is merged and
released, the negative assertion could be removed.
Signed-off-by: silverwind <me@silverwind.io>
Co-authored-by: silverwind <me@silverwind.io>
