Add one time force refresh ability for CachedAsyncImage and AvatarView

[pinarol]

Closes Described here #615 (review) (see "it does not refresh" part)

Description

We need to force refresh the avatar just once when the avatar selection changes. Previously I did that by setting forceRefresh to true and then false with a little delay but sometimes the underlying system can ignore the true value somehow. So I added a new binding just for one time refreshing purpose, which is actually the real need here. This way we can set the flag back to false after the call is really done.

Testing Steps

• Switch between avatars many times or delete the selected avatar
• Make sure the avatar in the QE's profile card gets updated

[wpmobilebot]

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

	App Name	Gravatar Prototype Build
	Build Number	2042
	Version	1.0
	Bundle ID	com.automattic.gravatar-sdk-demo-uikit.prototype-build
	Commit	7b9ef0a
	App Center Build	Gravatar SDK Demo - UIKit #565

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

[andrewdmontgomery]

This approach looks better. Nice. Testing seems to work great, too. I ran into a bug, but it's happening on the release/3.2 branch also. And to some degree, it also happens on the release/3.1.1 commit. I'll create an issue.