Add security fix backported from 9.4:

• [security] Bad chevrons rendering on dropdowns (#5468)
• [security] Iframe and forms are rendered in rich text contents (#5519)
• [security] Type juggling authentication bypass (#5520)
• [security] Malicious images upload (#5580)
• [security] Password token date was not reset (#5577)
• [security] Prevent timed attack and enforce cookie security (#5562)