Add a settings props for customization

[bourdakos1]

We have a few established user experiences that are either too "opinionated" or too established to modify. We should introduce settings to test out alternatives. Some examples:

• file extensions: This is 100% a user preference. The user should be able to decide if they want to show the full file name example.ipynb or the name without the extension example. (default: show file extension)
• double click behavior: Double clicking on a file opens a node, but this is arguably not the best for various reasons (not all nodes have a file tied to them, clicking on a node changes the active properties, opening a flyout panel is an established pattern in other products, etc...). However, current Elyra users may be too accustomed to it opening a file. The user should be able to decide whether double click opens properties or opens the file. (default: open properties)
• scroll to zoom: The user should be able to decide whether or not the canvas will zoom in/out when scrolling, this behavior might not be used by many and the effect of an accidental scroll can be a bit jarring for some users. (default: disabled)