feat: option to collapse long notes

What

Add an option to re-collapse long messages.

Why

Opening long messages on the timeline can make it hard to scroll back and forth, that mostly results in a "meh, I'll just refresh the page"

Additional info (optional)

Please give me a string value for "Show less" in Japanese, Got a tip to use "閉じる", if it's not the right one, let me know. As I understand, the new keyword will get into the flow if it has a Japanese value, the rest come from Crowdin (that's why I did not commit any other languages/translations).

Closes #8559 (closed)