Improve discoverability of the permalinks tab

Feedback from one of our academic journal users seems to indicate that the importance and value of the red Permalinks vertical tab is not as self evident as we thought. Once we show its use, it is immediately understood, but when a newcomer looks for the permalink, that's another story. We want to attract the attention of newcomers to this important feature, without changing the current UI.

For this, add a non intrusive animation as follows:

• when a new users gets to a code browsing page in the archive, the vertical red tab slowly slides into place from right to left (this attracts attention, it should be enough to invite a new user to explore it)
• the animation is disabled as soon as the new user opens up the Permalinks tab (a cookie can be set for this when the tab is opened)

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Migrated from T3196 (view on Phabricator)