Related to: #586.
Adds a loading state to stickers, so that a loading indicator appears while the sticker is being downloaded from IPFS.
In the case of a network failure or timetout, a reload button is shown instead. Once network is restored and the reload button is clicked, the image is reloaded from the network, going through the same lifecycle of showing the loading state first.
Add sticker popup
Add send sticker message
Add ability to select sticker pack and show stickers for pack with scroll
1. Sticker history
2. Install sticker packs
3. Sticker market
1. Sticker packs are installed on app start up until installation of sticker pack functionality is added
2. Optimisations such as preloading images to be done so that sticker images are not downloaded each time.