Lambda cleanup Jan 2022

[TonyLB]

• Abstract a Utility lambda layer to share #237
• Revise Asset to abstract away from DynamoDB #220
• Revise Ephemera to abstract away from DynamoDB #221
• Refactor Ephemera connection storage so it doesn't require a Scan #241
• Make Asset Character dynamoDB handler update Ephemera Player record #234
• Revise Message to abstract away from DynamoDB #222
• Revise controlChannel to abstract away from DynamoDB #223
• Abstract selfHealing functions into utility layer #239
• Make sure doubled targets (e.g. CHARACTER and ROOM) don't double-deliver messages #157
• Refactor ephemera Character Handlers to reduce repeated code #155
• Denormalize Color into CharacterInPlay Ephemera #150
• Prevent race-condition in which refreshing character isn't present in WhoDrawer #149
• Extend not-character targets in message delivery #141
• Investigate whether dynamoDB client can be removed from lambdas that share utility layer #240
• Generalize dynamoDB utility calls to reduce repeating yourself in that code #244
• Abstract Websocket Post calls into lambda utility layer #248