Forms: optimistically update count in sidebar for read/unread actions

[simison]

Builds on top of:

• Forms: add read/unread state to the UI #45350

Proposed changes:

Pay attention to the counters in the sidebar:

Before

WIP

After

WIP

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
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Jetpack product discussion

Does this pull request change what data or activity we track or use?

Testing instructions:

• Go to '..'

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WoA dev site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin (Jetpack), and enable the add/forms-unread-state-optimistic-updates branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack add/forms-unread-state-optimistic-updates

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• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
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• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[github-actions]

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[jp-launch-control]

Code Coverage Summary

Coverage changed in 9 files. Only the first 5 are listed here.

File	Coverage	Δ%	Δ Uncovered
projects/packages/forms/src/dashboard/inbox/dataviews/actions.js	0/126 (0.00%)	0.00%	40 💔
projects/packages/forms/src/dashboard/inbox/utils.js	0/20 (0.00%)	0.00%	15 💔
projects/packages/forms/src/contact-form/class-contact-form-endpoint.php	625/708 (88.28%)	-0.53%	10 💔
projects/packages/forms/src/dashboard/inbox/response.js	0/92 (0.00%)	0.00%	9 💔
projects/packages/forms/src/dashboard/inbox/dataviews/index.js	0/132 (0.00%)	0.00%	6 💔

Full summary · PHP report · JS report

_{If appropriate, add one of these labels to override the failing coverage check: Covered by non-unit tests Use to ignore the Code coverage requirement check when E2Es or other non-unit tests cover the code Coverage tests to be added later Use to ignore the Code coverage requirement check when tests will be added in a follow-up PR I don't care about code coverage for this PR Use this label to ignore the check for insufficient code coveage.}

[simison]

Follow-up in #45425