Add FXIOS-7395 [v120] Link button (#16858)

* Create link button in component library

* Add sample app link button example

* Make adjustment to link button config

* swiftlint

BrowserKit/Sources/ComponentLibrary/Buttons/LinkButton.swift

@@ -0,0 +1,44 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/
+
+import Common
+import UIKit
+
+public class LinkButton: ResizableButton, ThemeApplicable {
+    private struct UX {
+        static let buttonCornerRadius: CGFloat = 13
+        static let buttonVerticalInset: CGFloat = 12
+        static let buttonHorizontalInset: CGFloat = 16
+    }
+
+    override init(frame: CGRect) {
+        super.init(frame: frame)
+
+        backgroundColor = .clear
+        titleLabel?.adjustsFontForContentSizeCategory = true
+        contentEdgeInsets = UIEdgeInsets(top: UX.buttonVerticalInset,
+                                         left: UX.buttonHorizontalInset,
+                                         bottom: UX.buttonVerticalInset,
+                                         right: UX.buttonHorizontalInset)
+    }
+
+    public func configure(viewModel: LinkButtonViewModel) {
+        accessibilityIdentifier = viewModel.a11yIdentifier
+        setTitle(viewModel.title, for: .normal)
+        titleLabel?.font = DefaultDynamicFontHelper.preferredFont(withTextStyle: .body,
+                                                                  size: viewModel.fontSize)
+        titleLabel?.textAlignment = viewModel.textAlignment
+    }
+
+    required init?(coder aDecoder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+
+    // MARK: ThemeApplicable
+
+    public func applyTheme(theme: Theme) {
+        setTitleColor(theme.colors.textAccent, for: .normal)
+        setTitleColor(theme.colors.actionPrimaryHover, for: .highlighted)
+    }
+}

BrowserKit/Sources/ComponentLibrary/Buttons/LinkButtonViewModel.swift

@@ -0,0 +1,24 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/
+
+import UIKit
+import Foundation
+
+/// The view model used to configure a `LinkButton`
+public struct LinkButtonViewModel {
+    public let title: String
+    public let a11yIdentifier: String
+    public let fontSize: CGFloat
+    public let textAlignment: NSTextAlignment
+
+    public init(title: String,
+                a11yIdentifier: String,
+                fontSize: CGFloat = 16,
+                textAlignment: NSTextAlignment = .left) {
+        self.title = title
+        self.a11yIdentifier = a11yIdentifier
+        self.fontSize = fontSize
+        self.textAlignment = textAlignment
+    }
+}

BrowserKit/Sources/ComponentLibrary/Documentation.docc/General Components/LinkButton.md

@@ -0,0 +1,19 @@
+# ``ComponentLibrary/LinkButton``
+
+The button which is used for actions that looks like a webview link.
+
+## Overview
+
+The `LinkButton` is a subclass of the `UIButton`. This means properties of the `UIButton` are accessible, but for easy conveniance it's recommended to configure the button title, font and accessibility identifier through it's' view model ``LinkButtonViewModel``. The colors and spacing of the button although accessible shouldn't be adjusted and should be used as is.
+
+## Illustration
+
+> This image is illustrative only. For precise examples of iOS implementation, please run the SampleApplication.
+
+![The LinkButton on iOS]LinkButton
+
+## Topics
+
+### View Model
+
+- ``LinkButtonViewModel``

SampleComponentLibraryApp/SampleComponentLibraryApp/Buttons/ButtonsViewController.swift

@@ -14,6 +14,7 @@ class ButtonsViewController: UIViewController, Themeable {
 
     private lazy var primaryButton: PrimaryRoundedButton = .build { _ in }
     private lazy var secondaryButton: SecondaryRoundedButton = .build { _ in }
+    private lazy var linkButton: LinkButton = .build { _ in }
 
     private lazy var buttonStackView: UIStackView = .build { stackView in
         stackView.distribution = .fillEqually
@@ -46,14 +47,20 @@ class ButtonsViewController: UIViewController, Themeable {
                                                                  a11yIdentifier: "a11ySecondary")
         secondaryButton.configure(viewModel: secondaryViewModel)
 
+        let linkButtonViewModel = LinkButtonViewModel(title: "This is a link",
+                                                      a11yIdentifier: "a11yLink")
+        linkButton.configure(viewModel: linkButtonViewModel)
+
         primaryButton.applyTheme(theme: themeManager.currentTheme)
         secondaryButton.applyTheme(theme: themeManager.currentTheme)
+        linkButton.applyTheme(theme: themeManager.currentTheme)
     }
 
     private func setupView() {
         view.addSubview(buttonStackView)
         buttonStackView.addArrangedSubview(primaryButton)
         buttonStackView.addArrangedSubview(secondaryButton)
+        buttonStackView.addArrangedSubview(linkButton)
 
         NSLayoutConstraint.activate([
             buttonStackView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20),