Do not enable delayed expansion mode when running cmd.exe

And simplify the argument escaping code. Fix #3764.

This may breaks some existing use cases, but the mode causes too much
trouble when escaping arguments and it makes some things not possible.

  # Now you can pass special characters to rg process without any escaping problems: &|<>()@^%!
  fzf --ansi --disabled --bind "change:reload:rg --column --line-number --no-heading --color=always --smart-case -- {q}"

  # No sudden expansion of the arguments on '!'
  fzf --disabled --preview "echo {q} {n} {}" --query "&|<>()@^%!" --prompt "&|<>()@^%!"

src/util/util_windows.go

@@ -42,7 +42,7 @@ func NewExecutor(withShell string) *Executor {
 		args = args[1:]
 	} else if strings.HasPrefix(basename, "cmd") {
 		shellType = shellTypeCmd
-		args = []string{"/v:on/s/c"}
+		args = []string{"/s/c"}
 	} else if strings.HasPrefix(basename, "pwsh") || strings.HasPrefix(basename, "powershell") {
 		shellType = shellTypePowerShell
 		args = []string{"-NoProfile", "-Command"}
@@ -119,8 +119,6 @@ func escapeArg(s string) string {
 			slashes = 0
 		case '\\':
 			slashes++
-		case '&', '|', '<', '>', '(', ')', '@', '^', '%', '!':
-			b = append(b, '^')
 		case '"':
 			for ; slashes > 0; slashes-- {
 				b = append(b, '\\')