Strings with escaped characters are missing double-quotes

```console
❯ yq --version
yq (https://github.com/mikefarah/yq/) version v4.48.1

❯ yq -n '.foo = "a\tb"'
foo: a\tb
```

The output is not correct; backslash escapes only work inside double-quoted strings. The output should have been:

```console
❯ yq -n '.foo = "a\tb"'
foo: "a\tb"
```