Improvements to Library Header

[jmakowski1123]

[marcotuts]

Header Updates:
1 - Page Title: Keep Library Title as primary header
2 - Page Subtitle: Ok to keep "Content Library" as the label above the Library title, even though that is not reflected in the visual above.

Page Actions: (NO CHANGES)
1 - Library Info --- NO Changes
2 - + New --- NO Changes - ignore the "Add Content" label shown in screenshot above.

SubNavigation
1 - This should move to be underneath the page header and page actions, with no line separator between them. Whatever our existing light gray is should be shown as the background color in the area above the sub-navigation
2 - The tabs that exist today (All Content | Collections | Components) should remain with no changes - we are not renaming this to "Home" or adding Units / Subsections / Sections.

Search Box
1 - This should move to being inline with the header and underneath the subnavigation tabs.

Filters / Sort Options
1 - Tags + All Types should appear inline with search, with no behavior change expected.
2 - No changes to Sort options
3 - We are not adding the grid vs list view in this scope even thoug hthe image shows this above.

The background color of the search + filter area should match the rest of the page below and be white #fff