Make it work with Stripe

[conatus]

Description

Motivation and Context

How Can It Be Tested?

How Will This Be Deployed?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I've checked the spec (e.g. Figma file) and documented any divergences.
• My code follows the code style of this project.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I've updated the documentation accordingly.
• Replace unused checkboxes with bullet points.

[conatus]

1. Replace all this stuff - https://github.com/commonknowledge/join/blob/master/packages/join-block/lib/services/join_service.php#L19-L266 with the Stripe equivalent.
2. Add any corresponding code needed on the front end join flow, remembering the Monorail app does this - https://github.com/commonknowledge/ckmap/tree/main/ckmap
3. Clean up any files that are lying around that reference the old stuff, like the GoCardless service and so on.
4. Remove any dependencies that are about GoCardless or ChargeBee.
5. Done!

[conatus]

Wiring in the React code to Monorail:

• Wiring in Stripe - https://github.com/commonknowledge/ckmap/pull/76/files - in particular - https://github.com/commonknowledge/ckmap/pull/76/files#diff-0b40908f918d9d7a3fc686979423a542ce12807929efb190e3b65dfd255b088c
• Finishing this off - https://github.com/commonknowledge/ckmap/pull/77/files

Probably don't need these levels of modularity here, but the component for interracting with Stripe looks like it could be copied into this code.