Add a toggle for the iga identity check

Since we may not want to enable the identity check, it must be togglable. This commit adds environment variable REACT_APP_ENABLE_IGA_CHECK for toggling the check in the frontend, and django settings variable IGA_CHECK for toggling the check in the backend.

frontend/src/components/identityLine/index.tsx

@@ -6,7 +6,7 @@ import { fetchJsonOpts, submitJsonOpts } from 'utils'
 import CheckIcon from '@mui/icons-material/Check'
 import { Trans, useTranslation } from 'react-i18next'
 import { TableCell } from 'components/table'
-import { appInst, disableNinVerification } from 'appConfig'
+import { appInst, disableNinVerification, enableIgaCheck } from 'appConfig'
 
 interface IdentityLineProps {
   text: string
@@ -85,7 +85,7 @@ const IdentityLine = ({
   }
 
   useEffect(() => {
-    if (confirmOpen && identityCheckText === null) {
+    if (enableIgaCheck && confirmOpen && identityCheckText === null) {
       fetchIdentityCheckText(identity.id)
     }
   }, [confirmOpen])