With this commit, messages can be pinned on a channel and chat conversation. There's a new menu listing all pinned messages on a conversation, and we can jump to these messages in the current conversation. As this feature incentives to see older messages, this commit also adds a "Jump to Present" button when looking at old messages. closes odoo/odoo#116666 Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>