add exported_column with its type

Co-authored-by: mfo <mfo@users.noreply.github.com>

app/models/exported_column.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+class ExportedColumn
+  attr_reader :column, :libelle
+
+  def initialize(column:, libelle:)
+    @column = column
+    @libelle = libelle
+  end
+
+  def id = { id: column.id, libelle: }.to_json
+end