[a11y] Hide emojis from view, synchronised across all apps

People with certain psychological diagnostics may struggle with seeing certain emojis, such as flashing animated emojis, emojis with jittery or quick animations, or emojis containing certain things that could trigger reactions as a result.

Add an option in the context menu to hide emojis automatically after being selected to be hidden. It should apply cross-device on all apps. A list of hidden emojis should be in the accessibility menu, in case they need to be accessed or removed from that list. The emojis should be automatically hidden in the selection menu for users as well, should they be in communities where the emojis originate from.