Update Path Expansion Page

[garrettmflynn]

fix #381

• A complete example is contained in the information toggle previously defined with an external link
• The information toggle is automatically open when the user firsts visits the page (i.e. if Yes / No has not been selected yet)
• A box shows beneath each format_string_path input with the current source file matches, while the full metadata is printed to the console

In attempting to implement all the suggestions, I decided it wouldn't be worthwhile to approach (3) and parts of (4) without further discussion.

• Auto-populating the format_string_path input is too unpredictable what the user might want (e.g. for the tutorial pipeline, I don't have enough knowledge to select a Phy folder or a SpikeGLX-related file if both exist at the lowest level of the base_directory)
• Listing out all the entities in the base directory will almost always be a lot of files / folders—too many to show nicely in a naive way.

Are there alternative approaches that y'all would suggest or something that I haven't implemented here that you'd like to see still?

[garrettmflynn]

Based on our discussion today, we can wait for an implementation of (3) based on #397. This PR should be good for review.

[CodyCBakerPhD]

I like. Will get @bendichter's feedback on this during that one on one alpha test