Wrap filenames in quotes only for Windows CMD

[joelim-work]

• Fixes Setting 'map e $nvim $Env:f' does not work for shell pwsh #1370

Filenames are wrapped in quotes when exporting them as environment variables to deal with Windows CMD, although it causes issues with PowerShell. Logic is added to check if the shell is cmd or not, similar to

lf/os_windows.go

Lines 104 to 105 in 2620f49

	// Windows CMD requires special handling to deal with quoted arguments
	if strings.ToLower(gOpts.shell) == "cmd" {