Feature/287 trainingplan approval gui

This merge request contains GUI pages to manage training plans that are requested by research, registered or saved as default.

To review:

• Please make sure model_approval is set to True in the node config file.
• After model approval is enabled start the node to create hashes for default models. Starting the node adds default training plans into database. Otherwise, there will be no default training plans saved in database.
• start GUI

./scripts/fedbiomed_run gui config <config-file-name> --data-folder <path-where-all-dataset-files-are-stores> -rc start

• go to localhost:8484/