[Playground] JSON rendering is not escaped

[zyc9012]

The rendered JSON shouldn't have line breaks.

instead of showing

"snippet": "a

b

c",

it should show

"snippet": "a\n\nb\n\nc",

Playground

It's the same kind of issue as https://github.com/serpapi/public-roadmap/issues/287, but this time in Playground and Search inspector.