Implement front end styling changes to adv. data page/feed

[PaulClark2]

This issue was moved over from the web app and specified. Original issue: fecgov/openFEC-web-app#2330

What we're after This set of changes prepares the advanced data page template to receive the data catalog data that was mapped into each section. It focuses on adjusting the styling, but stops short of adding the content in, which will be addressed in a separate issue. It's broken down this way to keep the issues small and manageable.

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Designs from fecgov/openFEC-web-app#2318

🖥 Invision prototype

This prototype shows how we might distribute the different data sets (from the data catalog and the FTP). The accordions are clickable and indicate how we might label and group data by year, as well as how we can create the space to describe the data within it.

Basic page styling:

Basic expanded accordion styling, and differences in accordion content

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Completion criteria

• Change advanced data template styles to match designs
  • Removes "feed" styling (removes lines between each item and nested/structured/indented relationships between data sets
  • Removes document icon for collected data sets
  • Changes data set titles to all h4
  • Adds magnifying icon in front of each searchable data set: this helps keep the focus on these features
• Create/Edit accordion pattern to match the design
  • Change body copy from serif to sans-serif
  • Prepare to accommodate icons, links, headers, and body paragraph styles within the panel
  • The work for this issue should create the styling and markup for the accordion patterns used on the page (Starting with and updating the accordion in the pattern library), but should not place them into the page yet: it's just to prepare the template for being filled.
• Update accordion pattern in pattern library
  The only other place on the site using our stock pattern accordions right now (that I know of) is the latest updates page. so if there's time:
  • Update accordion pattern on latest updates page to match new styling. (If there isn't time, separate this out into a smaller issue that would be easy to pick up)
• Check mobile styling