Newsletter settings: split subscription_options into its own options

[enejb]

Proposed Changes

• Splitting the Newsletter Settings options into two we avoid the settings not save issue. Such as sending the subscription_options options field even though it was never changes.

I tried to fix this with #90294 PR but this introduces some strange behaviour that I wasn't able to remedy.

There should be no visible changes to the form.

You should see the form

Testing Instructions

• Load this PR.
• Navigate to the Newsletter settings.
• Try saving the different settings.
• Make sure that they work as expected.

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?

[github-actions]

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[matticbot]

Here is how your PR affects size of JS and CSS bundles shipped to the user's browser:

Sections (~54 bytes added 📈 [gzipped])

name                 parsed_size           gzip_size
settings-newsletter       +404 B  (+0.1%)      +54 B  (+0.0%)

Sections contain code specific for a given set of routes. Is downloaded and parsed only when a particular route is navigated to.

Legend

What is parsed and gzip size?

Parsed Size: Uncompressed size of the JS and CSS files. This much code needs to be parsed and stored in memory.
Gzip Size: Compressed size of the JS and CSS files. This much data needs to be downloaded over network.

Generated by performance advisor bot at iscalypsofastyet.com.