customize export columns

[itsmicaio]

This PR adds possibility to customize columns.

how to use:

• create array of columns:

  const exportColumns = [
  {
  name: 'coupon',
  key: 'code', // key of record param
  callback: (value: string) => `30#${value}`, // optional callback to transform data
  },
  {
  name: 'name',
  concat: { // concat a list of record params by param key
    keys: ['firstName', 'lastName'],
    separator: ' ',
  },
  },
  {
  name: 'products',
  concat: { // concat an array record param
    key: 'products',
    separator: ', ',
  },
  }
  ]

• add options to feature builder

  const adminJsOptions = {
  ...
  features: [
    importExportFeature({
      export: {
        columns: exportColumns
      },
      import: {
        isVisible: false
      }
    })
  ],
  ...
  }