Random UX improvements to session recording player

[paolodamico]

This issue groups several minor UX improvements that have been discussed in different places:

• Add timestamps to the timeline pages
• Fade away bottom of event timeline list to indicate that there are more items available (following Show gradient on scrollable Select elements #2453)
• Show additional user information when hovering the user's email address
• Change the active state of the speed indicator to make it more obvious which speed is selected
• Use command palette's feedback bar
• Vary go back X seconds with a speed factor (e.g. going back 4 seconds if you're at 16x is not really helpful)
• Automatically scroll the event timeline when the bottom is reached
• Very long user identifiers overflow the screen

Thank you for your feature request – we love each and every one!

[Twixes]

This is pretty much all solved with the new recordings player.