Rework NFT playground legacy UI elements

[armandomistral]

Background

The NFTs section contains certain legacy UI elements (layout, behavior and components) dating back from the NFT playground, which are no longer consistent with the latest Centrifuge App version. This ticket defines the parts that are to be reworked.

Acceptance criteria

The views listed below are updated according to the spec. The views are:

• NFT menu
• Create collection
• NFT collection
• Mint NFT
• NFT detail

Specification

Centrifuge App - Refactor NFT playground legacy elements (HackMD)