Update OAS and test definitions to remove IDENTIFIER_MISMATCH error code

[eric-murray]

What type of PR is this?

• correction

What this PR does / why we need it:

Commonalities has removed the IDENTIFIER_MISMATCH error for Fall25. Instead, a device identifier should not normally be included in responses. It should only be included to disambiguate the identity of the device when:

• the endpoint is being accessed using a 2-legged access token; and
• the endpoint allows for a device identifier to be provided in the request; and
• the API consumer has included multiple device identifiers

The response then includes the device identifier that was used by the implementation

This PR:

• Updates documentation in each OAS
• Adds relevant examples both for when device disambiguation is required, and when it is not required
• Uses DeviceResponse object for the device-data-volume API to limit device identifiers in responses to exactly one
• Removes the IDENTIFIER_MISMATCH error code option from 422 responses

Note; For subscriptions, the CreateSubscriptionDetail schema is used in both requests and responses, so modifying the responses to use the DeviceResponse would require a general update of the subscription schema in Commonalities. For the moment, the existing schema is left unmodified, which means that multiple device identifiers could be provided in responses, but should not.

Which issue(s) this PR fixes:

Fixes #50

Special notes for reviewers:

I think both GET endpoints should never return a device identifier in the responses, but haven't thought through all possible scenarios, so will raise this as a separate issue.

Changelog input

 release-note
 - Update documentation in each OAS
 - Add relevant examples both for when device disambiguation is required, and when it is not required
 - Use DeviceResponse object for the device-data-volume API to limit device identifiers in responses to exactly one
 - Remove the IDENTIFIER_MISMATCH error code option from 422 responses and test cases

Additional documentation

None

[maxl2287]

Thanks @eric-murray !