Implement v3.1.8 of the Read/Write API (excluding VRPs)

[matt-wills]

Story

As a customer of the OB Toolkit
I want to be able to use v3.1.8 of the Read/Write API
so that I can be sure I am compliant with the latest OB specifications.

Acceptance criteria

• v3.1.8 of the Read/Write API has been implements for:
  ** Payment Initiation
  ** Accounts
  ** Funds Confirmation
  ** Aggregated Polling
  ** Callback URL
  ** Events Subscription
• I can see the required v3.1.8 URLs in the Discovery API.

Note that this story does not cover Variable Recurring Payments, which will be provided by #36.

Tasks

• Analyse functional changes in spec and present list of issues to implement
• Generate new uk-datamodel classes.
• Generate new controller classes/interfaces with relevant changes.
• Update datamodel converter classes.
• Update config files (e.g. RS discovery config - application.yml - with active/inactive API versions).
• File payment functionality (see CSVFilePaymentConsentsApiController and PaymentFileType) in openbanking-reference-implementation.
• Update functional tests - add tests for new fields
• Check discovery endpoint
• Postman tests

Release Notes

Affected Apps:

• openbanking-aspsp
• openbanking-reference-implementation