vim-patch:9.2.0538: Cannot keep leading whitespace in %{} statusline expr (#40007)

Problem:  A leading space in the result of a %{} item is sometimes
          stripped, and an all-digit result is converted to a number.
Solution: Add %0{} atom which inserts the expression result verbatim
          (glepnir)

fixes:  vim/vim#3898
closes: vim/vim#20315

e8d7a40b98

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

runtime/lua/vim/_meta/options.gen.lua

@@ -6817,7 +6817,8 @@ vim.wo.stc = vim.wo.statuscolumn
 --- { NF  Evaluate expression between "%{" and "}" and substitute result.
 ---       Note that there is no "%" before the closing "}".  The
 ---       expression cannot contain a "}" character, call a function to
----       work around that.  See `stl-%{` below.
+---       work around that.  See `stl-%{` below.  Use "%0{" to insert the
+---       result verbatim.
 --- `{%` -  This is almost same as "{" except the result of the expression is
 ---       re-evaluated as a statusline format string.  Thus if the
 ---       return value of expr contains "%" items they will get expanded.
@@ -6926,6 +6927,8 @@ vim.wo.stc = vim.wo.statuscolumn
 --- A result of all digits is regarded a number for display purposes.
 --- Otherwise the result is taken as flag text and applied to the rules
 --- described above.
+--- 							*stl-%0{*
+--- With %0{ neither applies: the result is inserted as a literal string.
 ---
 --- Watch out for errors in expressions.  They may render Vim unusable!
 --- If you are stuck, hold down ':' or 'Q' to get a prompt, then quit and