Add (or move) self-contained-html option to the INI configuration file (pytest.ini)

[harmin-parra]

As discussed in the comments of #521, I would love to be able to set the self-contained-html option in the INI file.

I guess the fix would only require the addition of this piece of code:

parser.addini(
    "self-contained-html",
    type="bool",
    default=False,
    help="create a self-contained html file.",
)

The question would be:

Should the INI option name be identical to the command-line option (self-contained-html) ?
or should the dash be replaced by underscore (self_contained_html) ?

[BeyondEvil]

You can already achieve this by using addopts.

[pytest]
addopts =
    --self-contained-html