In Chrome, copying a block of code GitHub includes an HTML table with
both the line number and the line itself. This caused the paste function
to be fooled that a table should be inserted as Markdown instead of
plain text.

Now, we increase the requirements to determine for pasting a table by
comparing the HTML and text data:

1. The number of rows have to match
2. The max number of columns have to match

Note that we use the max number of columns in the tab-delimited text
because it's possible that a spreadsheet omits empty columns.

Closes https://gitlab.com/gitlab-org/gitlab/issues/195479