Unnecessary unescaping quotes in pageconfig

[jasongrout]

I think that this is probably not needed anymore:

jupyterlab/packages/coreutils/src/pageconfig.ts

Lines 81 to 86 in 860877e

	for (let key in configData) {
	// Quote characters are escaped, unescape them.
	configData[key] = String(configData[key])
	.split(''')
	.join('"');
	}

If it isn't needed, then unescaping like this can corrupt data (for example, if an attribute really has that escape sequence in it, it gets transformed to a quote)

I think #7016 especially means it is not needed.

This code was added in #2213

[blink1073]

Fixed in #7061