make `cursor_trail` work on the same command prompt only

Is your feature request related to a problem? Please describe.

Currently cursor_trail always shows cursor movement once the distance is beyond a certain threshold.

However, in most cases when the cursor makes a big movement, my eyes either know where it will land or don't care. For example,

• After typing in a long command and pressing "Enter", I know it will show up in the next command line prompt.
• When a program outputs long segments of text, I don't care where the cursor is.

However, the unnecessary animation in these scenarios is distractive.

The moments I see cursor_trail is only needed when I move cursor within a prompt buffer. For example, I may press Alt-F to jump a word, and the word has an unknown length to my eyes until I look carefully.

I tried to adjust cursor_trail_start_threshold and cursor_trail_decay, but they don't seem to be able to address the problem.

Describe the solution you'd like Add a new option cursor_trail_scenario to specify when to enable cursor movement.