feat: Trello board JSON import (#352)

Closes #27, closes #105

client/src/components/Boards/AddPopup/ImportStep.jsx

@@ -0,0 +1,51 @@
+import React, { useCallback } from 'react';
+import PropTypes from 'prop-types';
+import { useTranslation } from 'react-i18next';
+import { Button } from 'semantic-ui-react';
+import { FilePicker, Popup } from '../../../lib/custom-ui';
+
+import styles from './ImportStep.module.scss';
+
+const ImportStep = React.memo(({ onSelect, onBack }) => {
+  const [t] = useTranslation();
+
+  const handleFileSelect = useCallback(
+    (type, file) => {
+      onSelect({
+        type,
+        file,
+      });
+
+      onBack();
+    },
+    [onSelect, onBack],
+  );
+
+  return (
+    <>
+      <Popup.Header onBack={onBack}>
+        {t('common.importBoard', {
+          context: 'title',
+        })}
+      </Popup.Header>
+      <Popup.Content>
+        <FilePicker onSelect={(file) => handleFileSelect('trello', file)} accept=".json">
+          <Button
+            fluid
+            type="button"
+            icon="trello"
+            content={t('common.fromTrello')}
+            className={styles.button}
+          />
+        </FilePicker>
+      </Popup.Content>
+    </>
+  );
+});
+
+ImportStep.propTypes = {
+  onSelect: PropTypes.func.isRequired,
+  onBack: PropTypes.func.isRequired,
+};
+
+export default ImportStep;