feat: add JSON viewer to KeyContent

[lucasig11]

This PR:

• Adds the pink detail that provides visual feedback over the current working database;
• Fixes the Button component which required a property that has a default value (color);
• Adds a button which allows to toggle between the raw view of the key content and a JSON formatted one;

I implemented the JSON viewer using the 'react-json-view' library. I made it in a new component called 'ContentView', which I thought would make it easier to add other ways of formatting the output in the future.

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[caiodomingues]

That's really nice