Improve complete-popup on vertical screens

[dezza]

I suggest this can be improved:

I looked around for settings and none seem like a permanent fix (except switching to preview window obviously). Yes you can set pumheight=20 which will limit it vertically, but not horizontally in a sensible way afaik. It is dictated by the item length for each row word, kind, info, (functionname, args, markdown doc)

One could make a function for how occupied the screen is by the popup from the cursor, to act on it in completion.

def ColumnPct(in: number): number
  var onePct: float = ( &columns / 100.0 )
  var retPct: number = float2nr( in / onePct )

  return retPct
enddef

https://github.com/yegappan/lsp/blob/main/autoload/lsp/completion.vim#L315
If columns occupied by screen is 70%+

  if (ColumnPct(col('.') + longestMenu + longestWord) > 69)
    completeItems->map(((k, v) => (v->extend({'menu': ''}))))
  endif

As an example, just to make a screenshot to compare without the function-args signature.

The best ideas I could come up with quick:

1. Append the function-args removed from screenshot above into the actual info popup d.info as a separate header in the top. (https://github.com/yegappan/lsp/blob/main/autoload/lsp/completion.vim#L281-L288)
   I suggest a lsp-options for toggling this on/off by default. Some other lsp plugins have this. I would probably opt for this myself. Straight-forward way to quickly save a lot of rows for vertical screens.

2. Limit the func-name, func-args row in length, cut off by padding ".." to the right or both names and functions-args in length. It should be determined by both cursor pos, window size (columns) and the longest line-length in the info popup, which would ensure it never limits unnecessarily and always maximizes width.

Any other ideas?