Subscriptions block updates

[apeatling]

Update the email subscription block to significantly improve the settings for customizing the display and style of the form.

Before	After

Fixes #15076

Testing instructions:

• Insert a subscriptions form block on your site and try all of the new settings in the sidebar for customization.
• Save the post and confirm the settings and design updates pass through to the front end of the site.
• Add the subscription form widget to a widget area and confirm this still renders and works correctly.

To test old blocks:

• Add the block in master
• Check out this branch
• Check that the block looks ok in the editor and in the frontend

Proposed changelog entry for your changes:

• Will update this later.

[matticbot]

Caution: This PR has changes that must be merged to WordPress.com
Hello apeatling! These changes need to be synced to WordPress.com - If you 're an a11n, please commandeer, review, and approve D40775-code before merging this PR. Thank you!

[apeatling]

Status so far:

• Removed the subscriber count setting from the canvas to the sidebar.
• Moved the input field and submit button to a single line.
• Added support for gradients, border radius, and font sizing to the submit button.

In terms of styling I also think there needs to be control of:

• Input field border radius and font sizing
• Padding on both the submit button and input field
• Space between the input field and submit button
• Dropping the submit button down onto a new line
• Positioning and possibly more fine grained design control over the subscriber count text.

/cc @mtias

[mtias]

Nice work!

Input field border radius and font sizing

I think this should be a single control that always applies to both the button and the input to make it feel in concert.

[mtias]

I guess with the submit button being a "shared" resource we need to check impact on other blocks consuming it.

[apeatling]

Thanks! Will review this feedback this afternoon. With all the shared button changes the other blocks will definitely need an update, I can handle this once all the changes to this block are done. If it ends up being a large amount of work, I can separate the button changes and work on that in a different PR.

[apeatling]

I've now switched this to not use the shared submit button. Instead using standard controls and bringing the settings into the actual block itself. Styles are passed through and applied to both elements.

[jetpackbot]

	Warnings
⚠️	pre-commit hook was skipped for one or more commits

This is an automated check which relies on PULL_REQUEST_TEMPLATE. We encourage you to follow that template as it helps Jetpack maintainers do their job. If you think 'Testing instructions' or 'Proposed changelog entry' are not needed for your PR - please explain why you think so. Thanks for cooperation 🤖

Generated by 🚫 dangerJS against f0635f4

[apeatling]

Range control components don't seem to work correctly on zero values. For example try the buttons block and drag the border radius slider to zero. The value in the textfield remains at 5? The actual border radius is set as zero though. Known bug?

[mtias]

Mmm, yes, I'm seeing the same issue. Perhaps related to: WordPress/gutenberg#20247

[jeherve]

Approving once again after a rebase.

[jeherve]

Missed a commit in my last rebase.

[apeatling]

🎉

[Copons]

I've noticed that this PR hasn't been synced to WPCOM yet!
When you do this please note that I've done a tiny fix to the block icon in #15664.

[apeatling]

Will do this later today 👍

[apeatling]

@Copons Looks like this can't be merged until June 2nd according to @jeherve on the Phab diff.

[jeherve]

r208345-wpcom

[mkaz]

I came to the repo to submit a feature request, and here it is already done. ❤️