Create a function that creates a Write

[AdamSiekierski]

And later sends a message to Discord Webhook. It would be easier if we could just use Firebase Functions, but well, money

Function will sit at POST /v1/writes/create

Ticket name: function/create-write

[AdamSiekierski]

I will do the first part, @datejer the discord part, but we'll create a different ticket for that