PLATFORM-4908 Allow to add external image with custom url

[mmeller-wikia]

https://wikia-inc.atlassian.net/browse/PLATFORM-4908

Connected with https://github.com/Wikia/unified-platform/pull/4742

[mszabo-wikia]

Do we have a consensus on how we plan to implement this? This proposed implementation is different from the one submitted to upstream, and also different from the alternative suggested by upstream reviewers.

[mmeller-wikia]

@mszabo-wikia Original patch (link] was rejected.
Based on second part of comment
2) I think just adjusting EXT_IMAGE_REGEX to allow trailing query parameters would likely be (a) a smaller patch, and (b) wouldn't involve an extra hook invocation on every URL. I'd think this would be preferable.
We prepared this patch -> we don't think that MW will agree to add sophisticated regex that will match links like this https://static.wikia.nocookie.net/olympians/images/c/c0/Luke_Castellan-Viria.jpg/revision/latest/top-crop/width/300/height/300?cb=20170220004745

[mszabo-wikia]

Can't know that without having a conversation about it first ;)