[feature request] Add name field to registration page

[rgy-stripe]

Bug report Feature request

The registration screen only has an input field for the customer's email address. This is the minimal information you need, but it would be slightly more realistic to also include at least a name input field, e.g.:

This would make the sample infinitesimally more complicated but would probably help users in the long run because it would be closer to what they eventually would need to build.

When/if we make this change, we should also update https://stripe.com/docs/billing/subscriptions/build-subscriptions to make sure the samples match.

Describe the bug change

Changes would need to happen in following files:

• docs/content/billing/subscriptions/build-subscription.md — in the docs, update the sample
  client/register.html
• client/register.js – here, we'd need to update the emailInput to something more generic, like formInput
  We'd need to make these changes for each language in the /server directory.

Additional context

• Friction log
• Friction log fix tracking