Support JSON Arrays as Multiple Select Field on Import
Feature description
When importing JSON data with a multiple-selection field, the incoming data usually has a format like this:
{ field: ["choice a"] }
{ field: ["choice b"] }
{ field: [] }
{ field: ["choice a", "choice c"] }
When this is imported, the JSON serialization is taken verbatim as a "Short Text" field. When changing the type from "Short Text" to "Multiple Select", the various choices are not detected as expected. If the choices are fixed manually in the "Edit Field", after applying, all data in the column is lost because the Baserow doesn't understand the JSON syntax.