Create metadata sync button

[lcjohnso]

Current Behavior

Subject metadata is consider a fixed property by Caesar -- it is imported from the Panoptes subject only once and not updated. This happens either on first classification or when a backfill occurs.

Desired Behavior

Provide research teams the option to manually sync a workflow's metadata -- fetch current metadata from Panoptes for all existing subjects and replace existing entries. This action would be accessible via the web UI and by the Python Client.

Use Cases:

1. A project is created, Caesar is configured for a workflow, and the workflow starts collecting data. The research team decides to add a new retirement rule where one of the conditions is based on the value of a metadata field. Relevant subjects have already been classified and subject metadata imported. The sync button will allow new metadata fields to be ingested by Caesar for use in rules.
2. A project has configured a workflow to use training subjects and feedback, and the workflow has been configured in Caesar to perform differential subject retirement. After some time and classification intake, the research team realizes they made a mistake regarding the subject metadata, and need to update metadata keys and values. The sync button will allow corrected metadata to be updated in Caesar.

[lcjohnso]

for current manual process that this would replace, see https://stackoverflowteams.com/c/zooniverse/questions/414