Authentication Layouts (#994)

* Remove unused code in OnboardingScreen.
* Add FullscreenDialog layout and use in auth flow.

Bump minimum OS to 16.4/13.3.

* Add dynamic layout based on dynamic type size.

UnitTests/Sources/AttributedStringTests.swift

@@ -0,0 +1,46 @@
+//
+// Copyright 2023 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+@testable import ElementX
+import XCTest
+
+class AttributedStringTests: XCTestCase {
+    func testReplacingFontWithPresentationIntent() {
+        // Given a string parsed from HTML that contains specific fixed size fonts.
+        let boldString = "Bold"
+        guard let originalString = AttributedStringBuilder().fromHTML("Normal <b>\(boldString)</b> Normal.") else {
+            XCTFail("The attributed string should be built from the HTML.")
+            return
+        }
+        originalString.runs.forEach { XCTAssertNotNil($0.uiKit.font, "The original runs should all have a UIFont.") }
+        
+        // When replacing the font with a presentation intent.
+        let string = originalString.replacingFontWithPresentationIntent()
+        
+        // Then the font should be removed with an inline presentation intent applied to the bold text.
+        for run in string.runs {
+            XCTAssertNil(run.uiKit.font, "The UIFont should have been removed.")
+            XCTAssertNil(run.font, "No font should be in the run at all.")
+            
+            let substring = string[run.range]
+            if String(substring.characters) == boldString {
+                XCTAssertEqual(run.inlinePresentationIntent, .stronglyEmphasized, "The bold string should be bold.")
+            } else {
+                XCTAssertNil(run.presentationIntent, "The rest should be plain.")
+            }
+        }
+    }
+}