Reduces the min-width to 340px with several changes at lower
resolutions
* collapses create account into dropdown
* hides language button and user messages
* The search component is updated to include a search toggle which
can be used to hide and show the search input at lower resolutions
- this leads to a slight HTML change with caching implications,
it also moves away from a BEM usage which is not standard for this
repository.
* limits width of logo based on the dimensions we display
in mobile
Bug: T276566
Change-Id: I89d75843ca7e33e6de93af5d7c22e46b7249c4b7
6777c5b1fe