NFT app improvements

[ClemensLey]

• [x] The NFT class should store the following data: title, artist
• [x] The NFT page in the app should display the image in top, underneath the title in larger bold font (maybe H2 or H3) and beneath the artist (see https://flowbite.com/docs/typography/headings/#heading-two-h2)
• [x] On the homepage we should display flowbite cards as shown here: https://flowbite.com/docs/components/card/#card-with-image
• [x] On the mint page we should reposition the image to make it look nice
• [x] there should be a heading "List for sale" on the NFT site
• [x] It would be nice if the NFT on the NFT site would be bigger
• [x] If an NFT is listed, it should say "You listed this NFT for 2 LTC" for the seller
• [x] If an NFT is listed, it should have a button "Buy for 2 LTC" for the buyer
• [x] There should be a way to "unlist" an NFT
• [x] On the wallet it should say in the "Fund" section: "Click the balance reload button after funding"
• [x] On the mint page, we should have a caption "Mint NFT"
• [x] When an nft is minted, it should say "Congratiolations! You minted an nft. Click here to see it.". "Here" should link to the nft site
• [x] On the NFT site, there should be the tile in a big caption, then the author in normal text, then the image, then a small caption "List for sale", and then the list for sale form
• [x] On the NFT site, if you own an NFT and it is listed, it should not have a box with the listing price, instead it should just say "You listed this NFT for 2 RLTC"
• [x] We should hide the "List this NFT" when it is listed