fix: escape quotemarks in Tree (and JSON copied)

[satouriko]

BUG: when logging an object in which strings includes quotemark, for eg.

console.log({ a: 'asdfdsa"as\ndfdsf"df' })

displays & copies an invalid json: {"a": "asdfdsa"as\ndfdsf"df"}

The pull request proposes an attempt to fix that issue. It is changed to {"a": "asdfdsa\"as\ndfdsf\"df"}

Meanwhile, behavior logging a string should not be change:

console.log('asdfdsa"as\ndfdsf"df')

displays & copies

asdfdsa"as
dfdsf"df

[tencent-adm]

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