Image flaw checking should be different for translated content

[peterbe]

If a translated document has an external image like:

<img alt="" src="https://mdn.mozillademos.org/files/15704/opera-mac-select-2-closed.png">

before downloading that image, it should see if the en-US equivalent already has a opera-mac-select-2-closed.png and then the result should become:

<img alt="" src="/en-US/docs/Web/Foo/bar/opera-mac-select-2-closed.png">

And if it's already something like:

<img alt="" src="/en-US/docs/Web/Foo/bar/opera-mac-select-2-closed.png">

it should not be a flaw even though there exists no translated-content/files/fr/Web/Foo/bar/opera-mac-select-2-closed.png.

But there exists a lot of "translated images". E.g. translated-content/files/fr/learn/forms/html_forms_in_legacy_browsers/index.html has a https://mdn.mozillademos.org/files/16009/choix_chrome.png so in that case it should just download it because the filename is unique to French.