Support FORMAT_TEXT on recent chrome with self contained html

[csm10495]

Right now doing something like this:

import pytest

from pytest_html import extras

def test_ex(extra):
    print ("hey")
    extra.append(extras.text("Hello World!\n", "Hello Text"))

leads to something like this:

The problem is if you click the "Hello Text" link, chrome will close it immediately. This is a standard behavior as of recent chrome (https://stackoverflow.com/questions/46818033/opening-datatext-plain-window-in-chrome-showing-up-blank).

Can we come up with a different way to make the text openable/viewable in self contained html?

[christiansandberg]

Would the download attribute work perhaps?

https://www.geeksforgeeks.org/html-a-download-attribute/amp/

[csm10495]

@christiansandberg , I think so. Opened #278 to use that. Thanks!