Only create DM room when first message is sent

[turt2live]

Instead of eagerly creating a room, only create the room when a message is sent. This could also help us use the room list search as a way to start DMs if we wanted

[t3chguy]

I am certain this is a dup but cannot find it :'(

[jakewb-b]

Since my issue was closed as a duplicate, copying the specific requirement here, and changing title to be a little more descriptive.

• As a user sending a DM to someone I do not have an active DM conversation with
• I want the room to be created only when I first send a message (text, image or voice)
• So that the recipient receives the invite only when there is a message in the room