Add option for all payment plans to Paid Content block

### Impacted plugin

Jetpack

### What

I would like to create a reusable pattern with the Paid Content block that is future-proof and will account for payment plans that have not yet been added to a site

### How

In the current iteration of the Paid Content block, each payment plan needs to be selected even when those payment plans are associated with the same access tier. When selected, the ID of the payment plan(s) is added as a block attribute.

If I use this block in its current form on current content—or in patterns to be used for future content—and then one day add a new payment plan, it seems that I would also then need to update blocks on all old content. It should be possible to set this as "All plans" and _maybe_ one day a configurable set of grouped plans.

It's also very possible I'm missing something. :)

Start at the Jetpack Paid Content block and trace how payment plans are selected and stored as block attributes. Check how the block handles plans associated with access tiers, then verify that an “All plans” choice includes payment plans added later without requiring existing content or patterns to be updated.

Written by the indexing model from the issue text.