Add the sheet for expanding the space description. (#4475)

* Start working on space description

* Hook up presentation of the SpaceScreenDescriptionView.

* Make the SpaceScreenDescriptionView more accessible and apply a background colour.

* Refactor and move sheet presentation to the header view.

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Co-authored-by: amshak <85162587+amshakal@users.noreply.github.com>

AccessibilityTests/Sources/GeneratedAccessibilityTests.swift

@@ -583,6 +583,10 @@ extension AccessibilityTests {
         try await performAccessibilityAudit(named: "SoftLogoutScreen_Previews")
     }
 
+    func testSpaceHeaderTopicSheetView() async throws {
+        try await performAccessibilityAudit(named: "SpaceHeaderTopicSheetView_Previews")
+    }
+
     func testSpaceHeaderView() async throws {
         try await performAccessibilityAudit(named: "SpaceHeaderView_Previews")
     }