Restructure for animated gifs

Animated gifs can't go through the asset pipeline since they come out as
a single frame of the original animation. Previously, I had only a
couple of them and didn't have my assets structured very well. I had the
assets that needed to be passthrough copied alongside those that could
go through the pipeline. It wasn't bad since there weren't many
animations. I mapped just those to passthrough copy to go to a single
directory. This will become more fraught as I add more since there's
more opportunity for collisions. When mapping to an output directory, I
can't maintain the inner structure of that directory. The files are
flattened. I moved everything around, both to separate images that can
go through the pipeline from those which can't and to allow for a simple
passthrough copy that will maintain the directory structure so that each
blog post can have its own directory of passthrough copied animated gifs
in the build.

favicon/site.webmanifest

@@ -0,0 +1 @@
+{"name":"","short_name":"","icons":[{"src":"/android-chrome-192x192.png","sizes":"192x192","type":"image/png"},{"src":"/android-chrome-512x512.png","sizes":"512x512","type":"image/png"}],"theme_color":"#ffffff","background_color":"#ffffff","display":"standalone"}