vim-patch:9.1.0888: leftcol property not available in getwininfo() (#31349)

Problem:  leftcol property not available in getwininfo()
Solution: add leftcol property property (glepnir)

closes: vim/vim#16119

0a850673e3

Co-authored-by: glepnir <glephunter@gmail.com>

src/nvim/eval.lua

@@ -4800,6 +4800,8 @@ M.funcs = {
       	botline		last complete displayed buffer line
       	bufnr		number of buffer in the window
       	height		window height (excluding winbar)
+      	leftcol		first column displayed; only used when
+      			'wrap' is off
       	loclist		1 if showing a location list
       	quickfix	1 if quickfix or location list window
       	terminal	1 if a terminal window