Using PHPicker

[etoledom]

Closes #381

Description

Using PHPickerViewController instead of UIImagePickerController for picking on-device photos. UIImagePickerController is still used for the device camera, and both (camera and device photos) use the custom Image Cropper as photo editor.

Testing Steps

• Run the SwiftUI demo app.
• Open the Avatar Picker demo screen .
• Present the Avatar Picker.
• Add a new image.
  • Check that both options (Take photo and Choose image) work as expected.

[wpmobilebot]

📲 You can test the changes from this Pull Request in Gravatar SwiftUI Prototype Build by scanning the QR code below to install the corresponding build.

	App Name	Gravatar SwiftUI Prototype Build
	Build Number	1309
	Version	1.0
	Bundle ID	com.automattic.gravatar-sdk-demo-swiftui.prototype-build
	Commit	b37ff32ceb83a15aa36fd33a6b93c8a236b08b82
	App Center Build	Gravatar SDK Demo - SwiftUI #161

Automatticians: You can use our internal self-serve MC tool to give yourself access to App Center if needed.

[wpmobilebot]

📲 You can test the changes from this Pull Request in Gravatar UIKit Prototype Build by scanning the QR code below to install the corresponding build.

	App Name	Gravatar UIKit Prototype Build
	Build Number	1309
	Version	1.0
	Bundle ID	com.automattic.gravatar-sdk-demo-uikit.prototype-build
	Commit	b37ff32ceb83a15aa36fd33a6b93c8a236b08b82
	App Center Build	Gravatar SDK Demo - UIKit #162

Automatticians: You can use our internal self-serve MC tool to give yourself access to App Center if needed.