Debate page: show arguments

[Andrei0872]

• seed with arguments
• include arguments' tickets in moderator activity
• endpoint for fetching arguments for a given debate
• protect the endpoint: only auth user & user can access it
• page layout
• protect the client route
• expand an argument
• sticky section header(title, buttons) - moved to separate ticket
• fetch debate title from endpoint
• position sticky on navbar + section title - moved to separate ticket
• popover with actions