feat(api): API specification v2.20.0

* Accounts:
  * feat(account): Added pagination to `GET /users/{user}/likes` and fixed typo in operationId.
  * feat(account): Added `product` on `UserDetails` to know the product the user is using.
* Score Library:
  * feat(library): Added `collaboratorType` to `ResourceRights` to know if the user accessing a resource is the owner, user or group collaborator. Adjusted non-optional properties on `ResourceRights`.
  * feat(library): Added `date` to `ResourceCollaborator` with the date the collaborator was added.
  * feat(score): Added new `mainKeySignature`, `highlightedDate` and `organization` properties to `ScoreDetails`. Adjusted non-optional properties on `ScoreDetails`.
  * feat(score): Added new `purpose` property to `ScoreTrack`. Adjusted non-optional properties on `ScoreTrack`.
  * feat(score): Added new `googleDriveDisabled` option when copying score (`POST /scores/{score}/fork`).
* Flat for Education:
  * feat(edu): Some Flat for Education invitatons can be re-used multiple times.
  * fix(edu): Flat for Education invitatons can only be used to create `admin` or `teacher` accounts, fixed `organizationRole` enum.
  * feat(edu): Added new `verifyIfNotAlreadyInResourceLibrary` option to `POST /classes/{class}/assignments/{assignment}/copy` to avoid copying to the Resource Library if the assignment is already in it.
  * fix(edu): Fixed `ClassAttachmentCreation` enum values to reflect the current state of our product.
  * feat(edu): Added `playback` and `lti` properties to `AssignmentSubmission`.
  * fix(edu): `comments` object has never been available in `AssignmentSubmissionUpdate`, only in `AssignmentSubmission`.
  * feat(edu): Added `graded` state for submissions.
  * feat(edu): Added `organizationResources` library type to `GET /eduResources/libraries`, and added `organizationPublic` enum value to `EduResourcePrivacy`.
  * feat(edu): Added new `privacy` property to `PUT /eduResources/{resource}`
  * fix(edu): Removed unused property `alternateLink` from `MicrosoftGraphSubmission`.
* fix(schema): missing `required: true` on some POST/PUT bodies.

Author: gierschv