Start a new Thread by replying to a message in Timeline

[daniellekirkwood]

As a user I want to start a new Thread from a message in the Timeline.

Long press on message to open options > start Thread is an option >

• Design is here: https://www.figma.com/file/T309ztx0sNyOOK6NKVLHsK/Threads?node-id=1304%3A244131

Short press is not included in the MVP/P0 version of Threads.

Following matrix-org/matrix-spec-proposals#3440

• Add Reply In Thread option on long click
• Display threads in the appropriate thread timeline
• Send a regular message from threads
• Send a Reply message from threads
• Send a Quote message from threads
• Send an Edit event from within threads
• Indicate a message is a root thread (with a temp UI)
• Use relation type m.thread to start Threads
• Make sure that m.thread can be combined with m.in_reply_to to allow quote relies in threads

Added:

• When user clicks "Reply in Thread" the message bar gets the focus so user can type reply immediately without the need for extra click

[daniellekirkwood]

Needs-Product is a label on this issue because we need to reach a conclusion on the Short Press discussion.