UX enhancements

[jraddaoui]

• Remove unused filter drop-downs.
• Add apply and apply filters buttons.
• Change reset filters option.
• Make search buttons blue.
• Add header to digital files filters.
• Order aggregation buckets alphabetically.
• Limit width and center FAQ page content.
• Add tooltip for digital files filepath.

Refs #142, #144, #145, #146, #151, #158, #159, #160.

[codecov]

Codecov Report

Merging #163 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #163   +/-   ##
=======================================
  Coverage   85.64%   85.64%           
=======================================
  Files          31       31           
  Lines        1219     1219           
=======================================
  Hits         1044     1044           
  Misses        175      175

Impacted Files	Coverage Δ
search/helpers.py	100% <100%> (ø)	⬆️