Update block scaffolding to use the withNotices HOC

[scruffian]

In of #14884 we realised we were doing notices wrongly. We should update the block scaffolding to do it the right way.

Changes proposed in this Pull Request:

• Update the block scaffolding to use the withNotices HOC

Is this a new feature or does it add/remove features to an existing part of Jetpack?

• change to existing feature

Testing instructions:

• Run yarn docker:wp jetpack scaffold block "Cool block"
• Open the editor
• Try adding a "Cool block" to the editor.
• Check that the block loads correctly

Proposed changelog entry for your changes:

• no changelog

[jetpackbot]

Thank you for the great PR description!

When this PR is ready for review, please apply the [Status] Needs Review label. If you are an a11n, please have someone from your team review the code if possible. The Jetpack team will also review this PR and merge it to be included in the next Jetpack release.

Scheduled Jetpack release: April 7, 2020.
Scheduled code freeze: March 31, 2020

Generated by 🚫 dangerJS against 4bee796

[jeherve]

Part of me wonders if we shouldn't extract this into a shared function available to all blocks? Ideally, that function could also handle all kinds of notices, not just erors. Something like this:

export function displayNotice( message, noticeOperations, type = 'error' ) {
	noticeOperations.removeAllNotices();
	noticeOperations.createNotice( { status: type, content: message } );
}

[scruffian]

That might be worth trying in some blocks, but I'd rather we only move stuff into the scaffolding when we've already had success with it in other blocks.

[jeherve]

You're right. I suggested we give that a try in #14884 (comment)

Until then, we should be able to merge your PR and revisit once we have some blocks using it.