Add CI/CD configuration for SonarQube code analysis

See merge request fairdata/invenio-utilities-tuw!1

* soft-deleted files will have ObjectVersions that don't have an
  associated FileInstance

* it seems that during deletion of drafts, the references to those files
  are deleted from the DB, but the files are still kept on disk
* thus, we now consider files to be orphaned that are still present in
  the file system, but don't have entries in the database anymore

* per default, try the more modern approach of updating the draft that
  is associated with the record's recid (service.update_draft() followed
  by service.publish()), and only in case of error fall back to
  service.update()
* add a "direct" variant of updating metadata, which circumvents the
  record service and directly modifies the record's metadata
* this is not recommended, but can come in handy when more direct access
  is required than the record service allows

* this new option allows dumping of the JSON data as stored in the
  database, rather than the record/draft projection

* make --as-user option not required anymore, use system identity per
  default

* use the new metadata schema for owners in the owner-setting feature
  when creating new records

* as fallback, the parameter --as-user/-u now reads its value from the
  environment variable INVENIO_UTILITIES_TUW_USER (if it is set)
* thus, the --as-user/-u parameter doesn't have to be specified for each
  command anymore
* the value is still required, s.t. either the env var or the CLI option
  have to be specified

* note: this is *not* recommended, but can come in handy if the
        assignment of a specific PID is a requirement

* ignore E731 for flake8, which is a waning about using lambda vs def

* allow draft/record owners to be set explicitly when creating/updating
  drafts/records
* if specified, the owners will override the "access.owned_by" section
  in the record's JSON
* the implementation assumes that the record's JSON structure follows
  invenio-rdm-records

* get the DraftMetadata class from the record service instead of
  directly importing it from invenio-rdm-records
* prevents issues with renaming of the metadata class, etc.

* apply Black formatting
* use plural for sub-commands, for consistency
* fix convert_to_recid() to always fetch the first PID of type 'recid'
* add command to reindex all (or some) records
* update method for instantiating RecordServices: allow the configuration
  of a factory function that creates a RecordService as desired
  (default: fetches services from current_rdm_records)

* add command for listing soft-deleted files
* add command for listing all files of a record

* previously, the 'any_user' need wasn't added to a known user's identity

* add further commands for managing drafts
* add command for listing users

* add commands for listing/adding/removing files from drafts
* add commands for listing/deleting drafts