Fix Facebook videos if protocol isn't specified in data-href

[kzar]

Embedded Facebook videos are created by having a div element in the page that has (amongst other attributes) a data-href attribute that specifies the video's URL. The Facebook SDK then uses that to create the video iframe. Our "surrogate script" does the same.

It turns out that when the protocol prefix of that URL isn't specified (e.g. the URL starts '//'), then the SDK and our surrogate script need to take care to add the correct protocol to the URL (e.g. 'http:' or 'https:') based on the window location. Otherwise, the video fails to load.

Reviewer: @ladamski

Steps to test this PR:

1. Navigate to https://forums.spacebattles.com/threads/ace-combat-7-discussion-thread.366416/page-160?post=61183897#post-61183897
2. Click to load the Facebook video.
3. Ensure it loads and can be played.

Automated tests:

• Unit tests
• Integration tests

Reviewer Checklist:

• Ensure the PR solves the problem
• Review every line of code
• Ensure the PR does no harm by testing the changes thoroughly
• Get help if you're uncomfortable with any of the above!
• Determine if there are any quick wins that improve the implementation

PR Author Checklist:

• Get advice or leverage existing code
• Agree on technical approach with reviewer (if the changes are nuanced)
• Ensure that there is a testing strategy (and documented non-automated tests)
• Ensure there is a documented monitoring strategy (if necessary)
• Consider systems implications

[jonathanKingston]

LGTM; I'm guessing @ladamski needs to port it into his work but yeah seems good.

[ladamski]

Looks great, verified it works. Nice job!