aurweb: serve assets from nginx and cache properly

Make nginx serve static assets to offload gunicorn as for example loading the home page is making 7 static requests out of 8 requests in total. Set caching headers for now for 7 days, so browsers don't request ideally this would be 30 days but let's keep it 7 days for now.

Would be nice to have a way to invalidate these assets like archweb does by including a hash (?) in the filename. (cc @kevr)

Otherwise, looks good.

approved this merge request

added 13 commits

• 3081cd69...3430e875 - 12 commits from branch master
• 3399e17d - aurweb: serve assets from nginx and cache properly

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enabled an automatic merge when the pipeline for 3399e17d succeeds

mentioned in commit 6b652d3f

merged