Update Master Key back up and import flows

[stackingsaunter]

Part of #2917 epic

For detailed inspect of designs, see this Figma file

To do

• Update copy on both screens with new Popicons
• Illustration update (light and dark mode) and it goes below copy
• Add border 1px inner gray200 / dark: neutral700
• Change corner radius to rounded-2xl
• Put buttons inside the card, center and fix 256px (w-64)
• Cards should have p-10 padding (40px)
• Ideally, recovery phrase box with 12 words is narrowed and layout follows the one in Figma (doesn't have to be ideally the same though)

New illustrations:

Custom icon (not available in Popicons):

Screenshots