In most browsers we can use window.fetch. In others, like IE 11, this is not available.
To keep this simple for now reject the promise if native fetch is not available.

Added jest-fetch-mock for testing the "fetch is available" branch.

A convenience method to serialize a JS object into a query string, so it can be appended
to the URL (after '?').

This network client provides a fetchByTitle() function, to be used for typeahead search suggestions.
Not providing accept-language header at this time since it does not seem to make a difference.

By default the requests are mocked, so no network is used.
If the environment variable TEST_LIVE_REQUESTS is set to
a truthy value, the mocks are disabled and requests are made
against a live server.

A repeat of `title` doesn't seem useful to me.

Also undo in afterAll().
Plus a formatting fix.

Doing that I noticed that the null values need to be called out in the interface.

so it can be used by the UI for highlighting the search text.

Titles don't start or end with spaces. So, remove them, at least for title search.

The REST API documentation says it could return null for width or height. Make the value undefined in this case.

Clarify that the input object changes in one place where the thumbnail is null.