Allow custom SolidusImporter::Import strategy to read CSV files

[cesartalves]

Right now SolidusImporter::ProcessImport is reading the CSV file by doing a File.read on the import file path.

def scan
      data = CSV.parse(
        File.read(@import.file.path),
        headers: true,
        encoding: 'UTF-8',
        header_converters: ->(h) { h.strip }
      )
      prepare_rows(data)
end

However, on some projects that path may not be available depending on which customizations have been applied to Paperclip or ActiveStorage.
On a project I'm working on the files are sent directly to AWS, even on development, and their bucket path is interpolated in such a way that the @import.file local path can't be determined.

Therefore it would be useful to allow user-customizable strategies for reading the content from the file. E.g.:

SolidusImporter.config do |c|
  c.import_file_reader = -> (import) {
     open(@import.file.public_url)
  }
end

def scan
      raw_content = SolidusImporter::Config.import_file_reader.call(@import)
      data = CSV.parse(
        raw_content,
        headers: true,
        encoding: 'UTF-8',
        header_converters: ->(h) { h.strip }
      )
      prepare_rows(data)
end

Or any other approach may also be viable as long as we allow this to me easily customizable.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It might be closed if no further activity occurs. Thank you for your contributions.