Different result of getItemString and stringifyAndShrink depending on isWideLayout

[zalmoxisus]

This PR implements the following:

• Show only objects / arrays type for the preview when isWideLayout is false (fixes State view word wrapping makes state harder to read zalmoxisus/redux-devtools-extension#244).
• More detailed preview when isWideLayout is true.
• More detailed diff when isWideLayout is true (fixes Overly-aggressive string formatting in Diff output zalmoxisus/redux-devtools-extension#172).

[alexkuz]

My suggestions:

• Add text-overflow: ellipsis for preview in react-json-tree
• Leave at least 1 item in narrow layout (I think it will fit most of the times)

[zalmoxisus]

Sure text-overflow: ellipsis would do the trick, but we want truncation in middle. Not sure we want to see unterminated objects/arrays ({ key: ...).

1 item not always feats the narrow layout as well due to a long key (see pendingItemsLenderMarches). If it is not in the root the problem is even worse.

[alexkuz]

Sure, but as a last resort it's fine, I think, it's just a preview.

As for '1 item' - true, I just looked at real-life example, it would overflow quite often actually, especially in nested trees. Let's leave it 'zero'-sized then.