#43: Add the DesignKit package to the project.

* Add ElementTextFieldStyle and static style properties.
* Rename button styles, support sizes and simplify colour.

DesignKit/Sources/Shapes/RoundedCornerShape.swift

@@ -0,0 +1,32 @@
+// 
+// Copyright 2021 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.
+//
+
+import SwiftUI
+
+public struct RoundedCornerShape: Shape {
+    let radius: CGFloat
+    let corners: UIRectCorner
+    
+    public init(radius: CGFloat, corners: UIRectCorner) {
+        self.radius = radius
+        self.corners = corners
+    }
+    
+    public func path(in rect: CGRect) -> Path {
+        let path = UIBezierPath(roundedRect: rect, byRoundingCorners: corners, cornerRadii: CGSize(width: radius, height: radius))
+        return Path(path.cgPath)
+    }
+}