Gets a file's information from the Media Manager by fileUrl.
The getFileInfo() function returns a Promise that resolves to information about
the specified file.
The file's Wix media URL in the following format: 'wix:image://v1//#originWidth=&originHeight=[&watermark=]'.
Note: This replaces the old fileName parameter. fileName will continue to work, but we recommend that you use the updated fileUrl parameter instead.