Add default payment block plan name

[dsas]

Proposed Changes

When adding a new payment plan for the Jetpack Payment Button block to
use, the plan name will update depending upon the payment options
selected - whether it's a donation and what the payment frequency is.

This aids users in naming their plans appropriately. Making the form
faster to fill in accurately.

If the user explicitly chooses a name that differs from one of the
possible defaults, then that is respected and not overwritten.

Testing Instructions

1. Use the generated calypso preview link
2. On a site with a paid plan, go to Tools -> Earn in the menu
3. If you haven't already, follow the CTA to connect Stripe
4. Use 'Manage Payment Button' button
5. In the 'Manage Plans' section click 'Payment plans'
6. Press 'Add a new payment plan'
7. Notice that the plan name is defaulted to Monthly Subscription
8. Notice that as you use the donation and renewal frequency controls that it updates the plan name
9. Enter a completely custom plan name, notice that using the donation and renewal frequency controls no longer updates the plan name

trim_jJSyOR.mp4

The below image shows the contents of the textbox with the title:

Pre-merge Checklist

• 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)?

Related to Automattic/jetpack#24074, it's essentially the Calypso version of Automattic/jetpack#25397

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-39315

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-39315&env=jetpack

[matticbot]

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

Sections (~93 bytes added 📈 [gzipped])

name  parsed_size           gzip_size
earn       +332 B  (+0.1%)      +93 B  (+0.1%)

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.

[a8ci18n]

This Pull Request is now available for translation here: https://translate.wordpress.com/deliverables/7467252

Thank you @dsas for including a screenshot in the description! This is really helpful for our translators.

[a8ci18n]

Translation for this Pull Request has now been finished.