[FEATURE]: Convert homebrew APIv2 interface to JSON:API standard

[rixvet]

Re-write APIv2 interface to adhere to JSON:API 1.1 standard (https://jsonapi.org/) this will future-proof the APIv2 for new features and allow for more compact response.

Related to:

• [FEATURE]: Implement cursor based pagination #993

[zyronix]

Also looks like there is a standard for this:
https://datatracker.ietf.org/doc/html/rfc5988

The current status of this item:

In the current dev branch there is some pagination, however the server will fetch all data even if you just request two pages.

Please see:
https://github.com/hashtopolis/server/blob/dev/src/inc/apiv2/common/AbstractModelAPI.class.php#L298

In the feature branch of this issue this already has been partially implemented:
https://github.com/hashtopolis/server/blob/feature/1018-convert-homebrew-apiv2-interface-to-jsonapi-standard/src/inc/apiv2/common/AbstractModelAPI.class.php#L345

https://github.com/hashtopolis/server/blob/feature/1018-convert-homebrew-apiv2-interface-to-jsonapi-standard/src/inc/apiv2/common/AbstractModelAPI.class.php#L353

This need to be synced with the current dev branch. There needs to be some implementation of 'start-from-filter' in the SQL queries.

Beside the pagination, fetching of related object should also be done with the json-api standard (include).

Summary:

• Readup on json-api, https://jsonapi.org/format/#fetching-includes, https://jsonapi.org/format/#fetching-pagination
• Is include object fetching implemented in the attach branch?
• Is pagination implemented in the attached branch?
• Is filtering implemented in the attached branch?

Attached branch: https://github.com/hashtopolis/server/blob/feature/1018-convert-homebrew-apiv2-interface-to-jsonapi-standard