FEATURE: expand the admin sidebar when filtering (#27312)

Even when the admin sidebar sections are collapsed, they should expand while filtering. When the filter is removed, sections should go back to the previous state.

In addition, trim whitespace from the filter section.

spec/system/admin_sidebar_navigation_spec.rb

@@ -105,6 +105,29 @@ describe "Admin Revamp | Sidebar Navigation", type: :system do
     links = page.all(".sidebar-section-link-content-text")
     expect(links.count).to eq(3)
     expect(links.map(&:text)).to eq(["Appearance", "Preview Summary", "Server Setup"])
+
+    filter.filter("   preview   ")
+    links = page.all(".sidebar-section-link-content-text")
+    expect(links.count).to eq(1)
+    expect(links.map(&:text)).to eq(["Preview Summary"])
+    expect(page).to have_no_css(".sidebar-no-results")
+  end
+
+  it "temporarily expands section when filter" do
+    visit("/admin")
+    links = page.all(".sidebar-section-link-content-text")
+    expect(links.count).to eq(2)
+    expect(links.map(&:text)).to eq(["Dashboard", "All Site Settings"])
+
+    filter.filter("ie")
+    links = page.all(".sidebar-section-link-content-text")
+    expect(links.count).to eq(2)
+    expect(links.map(&:text)).to eq(["User Fields", "Preview Summary"])
+
+    filter.filter("")
+    links = page.all(".sidebar-section-link-content-text")
+    expect(links.count).to eq(2)
+    expect(links.map(&:text)).to eq(["Dashboard", "All Site Settings"])
   end
 
   it "allows further filtering of site settings or users if links do not show results" do