Redesign: timeline: message states

[bwindels]

• design all states for all contexts (e2e etc) with all content types (images/syntax/etc)
• consider compact mode
• consider increasing font size, and adding font size setting
• show sending / spinner next to message
• show resent / cancel options next to individual message
• restyle option at bottom of timeline to cancel / resent all failed messages.

[turt2live]

I'm going to close this in favour of modern tracking issues if/when we get them. If people have suggestions for modernized UX, please open new issues for consideration.