Print rest of line after cursor with large completion menu

[ysthakur]

Currently, if the buffer is too large to display all at once and you have a completion menu, the text after the cursor isn't displayed. Apparently, it's a difficult problem to show all of the text after the cursor that isn't covered by the menu, but this PR is only for showing the rest of the text on the same line as the cursor.

This is the current behavior. You can't tell which keys I'm pressing in the video, but when I type foo, then place my cursor before foo and hit tab to activate the completion menu, the foo disappears while my cursor is before it. If you move the cursor one word ahead, you'll see the foo again (my recording doesn't actually show this, I'll make a new one later when I'm not feeling so lazy but you should be able to reproduce on your own computer).

This is the new behavior (you can't see the stuff on lines after the current one, but at least you can see the rest of the current line):

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (b68ce33) 49.32% compared to head (583c591) 49.30%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #700      +/-   ##
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- Coverage   49.32%   49.30%   -0.02%     
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  Files          46       46              
  Lines        7988     7991       +3     
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  Hits         3940     3940              
- Misses       4048     4051       +3     

Files	Coverage Δ
src/painting/painter.rs	18.48% <0.00%> (-0.15%)	⬇️