#7879955 Storage Upgrade: update offer

Changes proposed in this Pull Request

This PR updates the products that are shown on the storage upgrade page to show Backup addons only (instead of plans).

Fixes 1182633034225700-as-1204031357952912.

Implementation notes

It’s kind of hard to comment on all changes since the code required a fair amount of changes to account for add-ons. Here are some pointer that I hope will help:

• Defined upgrade paths in the UPGRADES map use-get-storage-upgrade-products.ts.
• Added new hooks in packages/calypso-products/src/translations.tsx to facilitate translations of storage amount.
• Removed the duration check from the storage page, since the default never changed anyway (the route doesn’t consider duration). Upgrade relationships are defined in the UPGRADES map instead.
• Moved all copy in the useGetProductCardData hook.
• Removed the mentions of storage amount and backup days in the heading and subheading since they now depend on the add-ons being shown. This could be added back in a subsequent PR.

Testing instructions

• Make sure you have a Jetpack site with a monthly Jetpack Backup 10 GB subscription
• Spin up Calypso by running this branch locally, or clicking on a live link below
• Visit plans/storage/:site
• Check that you see the 10GB, 100GB, and 1TB addons upgrades
• Verify that the buttons behave as expected
• Pick a couple of monthly products in the table below, and check that you see the correct upgrades (one should not be able to upgrade from a monthly to a yearly plan, nor buy the add-on they already own)

Note: there may be some styling issues. This is due to styles not being loaded in the same order locally and in staging. Fixing this is not in the scope of this PR.

Screenshots

Before

After