Use a modern React context for identity in the app (#30098)

app/javascript/mastodon/features/firehose/index.jsx

@@ -6,13 +6,14 @@ import { useIntl, defineMessages, FormattedMessage } from 'react-intl';
 import { Helmet } from 'react-helmet';
 import { NavLink } from 'react-router-dom';
 
+import { useIdentity } from '@/mastodon/identity_context';
 import PublicIcon from '@/material-icons/400-24px/public.svg?react';
 import { addColumn } from 'mastodon/actions/columns';
 import { changeSetting } from 'mastodon/actions/settings';
 import { connectPublicStream, connectCommunityStream } from 'mastodon/actions/streaming';
 import { expandPublicTimeline, expandCommunityTimeline } from 'mastodon/actions/timelines';
 import { DismissableBanner } from 'mastodon/components/dismissable_banner';
-import initialState, { domain } from 'mastodon/initial_state';
+import { domain } from 'mastodon/initial_state';
 import { useAppDispatch, useAppSelector } from 'mastodon/store';
 
 import Column from '../../components/column';
@@ -24,15 +25,6 @@ const messages = defineMessages({
   title: { id: 'column.firehose', defaultMessage: 'Live feeds' },
 });
 
-// TODO: use a proper React context later on
-const useIdentity = () => ({
-  signedIn: !!initialState.meta.me,
-  accountId: initialState.meta.me,
-  disabledAccountId: initialState.meta.disabled_account_id,
-  accessToken: initialState.meta.access_token,
-  permissions: initialState.role ? initialState.role.permissions : 0,
-});
-
 const ColumnSettings = () => {
   const dispatch = useAppDispatch();
   const settings = useAppSelector((state) => state.getIn(['settings', 'firehose']));