RefreshTokenCredential component is missing in Device Data Volume Subscription

[dfischer-tech]

Problem description
The device-data-volume-subscriptions.yaml does not include the "RefreshTokenCredential" component.

Expected behavior
Add the component as referenced by the component "SinkCredential" property "credentialType" here
e.g.

    RefreshTokenCredential:
      type: object
      description: An access token credential with a refresh token.
      allOf:
        - $ref: "#/components/schemas/SinkCredential"
        - type: object
          properties:
            accessToken:
              description: REQUIRED. An access token is a previously acquired token granting access to the target resource.
              type: string
            accessTokenExpiresUtc:
              type: string
              format: date-time
              description: |
                REQUIRED. An absolute (UTC) timestamp at which the token shall be considered expired.
                In the case of an ACCESS_TOKEN_EXPIRED termination reason, implementation should notify the client before the expiration date.
                If the access token is a JWT and registered "exp" (Expiration Time) claim is present, the two expiry times should match.
                It must follow [RFC 3339](https://datatracker.ietf.org/doc/html/rfc3339#section-5.6) and must have time zone.
                Recommended format is yyyy-MM-dd'T'HH:mm:ss.SSSZ (i.e. which allows 2023-07-03T14:27:08.312+02:00 or 2023-07-03T12:27:08.312Z)
              example: "2023-07-03T12:27:08.312Z"
            accessTokenType:
              description: REQUIRED. Type of the access token (See [OAuth 2.0](https://tools.ietf.org/html/rfc6749#section-7.1)).
              type: string
              enum:
                - bearer
            refreshToken:
              description: REQUIRED. An refresh token credential used to acquire access tokens.
              type: string
            refreshTokenEndpoint:
              type: string
              format: uri
              description: REQUIRED. A URL at which the refresh token can be traded for an access token.
      required:
        - accessToken
        - accessTokenExpiresUtc
        - accessTokenType
        - refreshToken
        - refreshTokenEndpoint

Alternative solution

Additional context