Update KB for Easter Event

[amishshah]

KB is running an Easter Event!

Updating KB for this event will be based on what we already have for the KB Christmas Event (see the changes that were made in the Christmas event here)

This work should be done on the theme/easter branch.

Things that will need to change:

• Updating src/assets/chat_bg.png (find new file here)
• Updating src/assets/info.png (currently waiting for this asset to become available)
• Renaming "Christmas Event" in the app bar (desktop + mobile versions) to "Easter Event"
• (optional but recommended) there are some properties and functions specific to Christmas (e.g. onXmas). These could be renamed to onSpecialEvent to be a bit more generic and reusable.