Added first nf-core/stickers prototype

[FloWuenne]

This PR adds a very basic attempt at adding nf-core/stickers. Currently there is no navigation to the stickers page included in the main page and it can only be discovered via nf-co.re/stickers.
There are a couple of remaining issues:

• Bug when clicking hex sticker does wrong zooming, then corrects
• Grey box around hex sticker when using photoswipes navigation arrows to switch between stickers
  Can also
• Currently uses static svgs added to the website for testing. We probably want to point to raw github URLs instead so we don't have to update multiple instances of hexagon stickers everywhere

@netlify /stickers

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