Fix concurrency warning about editingDidFinish

[pinarol]

Closes #

Description

Swift implicitly assumes that editingDidFinish is an actor-isolated property(due to its use in a View protocol). To address this, we can explicitly mark the property as @MainActor, or alternatively, we can make editingDidFinish a @Sendable closure. I did the second which means we don't assume it must run on the main actor.

And then i got a new warning in our ImagePicker:

Even though ImagePicker is a View, the system this time doesn't automatically assume it runs on the main actor. So I added the @MainActor explicitly.

And then i got:

Then i put the call inside Task { ... }

Testing Steps

Test image picking & cropping.

[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	1523
	Version	1.0
	Bundle ID	com.automattic.gravatar-sdk-demo-swiftui.prototype-build
	Commit	a079fb38b3fc0f90d92ce0c71c5bbb2aa7bdd10d
	App Center Build	Gravatar SDK Demo - SwiftUI #283

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	1523
	Version	1.0
	Bundle ID	com.automattic.gravatar-sdk-demo-uikit.prototype-build
	Commit	a079fb38b3fc0f90d92ce0c71c5bbb2aa7bdd10d
	App Center Build	Gravatar SDK Demo - UIKit #284

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

[pinarol]

Closing this in favor of https://github.com/Automattic/Gravatar-SDK-iOS/pull/512