fix: spaces in FnSub literals are causing value to not be a literal

[mrgrain]

---

Template simplified for brevity.

{
  "Resources": {
    "Bucket": {
      "Type": "AWS::IAM::Role",
      "Properties": {
        "Description": { "Fn::Sub": "${!NoSpace}${ ! BothSpace}${! AfterSpace}${ !BeforeSpace}${!EndSpace }" },
      }
    }
  }
}