Places: New design for folder icons

[newhoa]

Combines the newer design of the system-file-manager app icon with the color palette of the current folder icons. Also adjusts the aspect ratio to make it slightly wider, so it is not quite as square as system-file-manager but not quite as wide as the current folder icons.

Closes #1305

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This is what has been done as of the initial PR:

• Basic folder at all sizes
• XDG User Directories at 48px and 64px
• folder-open (drag-accept) at 48px

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My initial thoughts/questions:

~1) I am thinking the 16px folder should be slightly less rounded?~ (went ahead and adjusted this) 2) I just added folder-open at 48px, feedback for that one would be appreciated before I start on any other sizes. 4) Is the aspect ratio of folder okay? (personally, I am liking it a lot the more I use them so I hope that can stick).

Any feedback would be appreciated!

Thanks!