fix(vim.system): resolve executable paths on windows

Fixes #31107

runtime/lua/vim/_system.lua

@@ -230,6 +230,8 @@ local function default_handler(stream, text, bucket)
   end
 end
 
+local is_win = vim.fn.has('win32') == 1
+
 local M = {}
 
 --- @param cmd string
@@ -238,6 +240,13 @@ local M = {}
 --- @param on_error fun()
 --- @return uv.uv_process_t, integer
 local function spawn(cmd, opts, on_exit, on_error)
+  if is_win then
+    local cmd1 = vim.fn.exepath(cmd)
+    if cmd1 ~= '' then
+      cmd = cmd1
+    end
+  end
+
   local handle, pid_or_err = uv.spawn(cmd, opts, on_exit)
   if not handle then
     on_error()