Add interstitial screen for Genome Browser and Entity Viewer (#510)

* Building the interstitials for the apps
* Show the interstitial on the EntityViewer page
* Fix tests
* Update styles for the BrowserInterstitialInstructions component
* Add nullability to a storage getter
* Add hide the in-app-search input field in production environment
* Reorder imports
11 jobs for master in 11 minutes and 59 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test Build Static
passed #492035
Test_N_Build

00:06:05

passed #492232
Test_N_Build:internal

00:03:25

failed #492036
Test_N_Build:internal

00:05:43

 
  Build Docker Images
passed #492039
Nginx:Internal

00:00:48

passed #492037
Nginx:Live

00:01:20

passed #492040
Node:Internal

00:00:51

passed #492038
Node:Live

00:01:15

 
  Deploy
passed #492044
Internal:HL

00:00:06

passed #492043
Internal:HX

00:00:06

passed #492042
Live:HL

00:00:08

passed #492041
Live:HX

00:00:08