Change icons in web UI (#27385)

Co-authored-by: Renaud Chaput <renchap@gmail.com>

app/javascript/mastodon/features/direct_timeline/components/conversation.jsx

@@ -8,6 +8,8 @@ import { Link, withRouter } from 'react-router-dom';
 import ImmutablePropTypes from 'react-immutable-proptypes';
 import ImmutablePureComponent from 'react-immutable-pure-component';
 
+import { ReactComponent as MoreHorizIcon } from '@material-symbols/svg-600/outlined/more_horiz.svg';
+import { ReactComponent as ReplyIcon } from '@material-symbols/svg-600/outlined/reply.svg';
 import { HotKeys } from 'react-hotkeys';
 
 import AttachmentList from 'mastodon/components/attachment_list';
@@ -178,7 +180,7 @@ class Conversation extends ImmutablePureComponent {
             )}
 
             <div className='status__action-bar'>
-              <IconButton className='status__action-bar-button' title={intl.formatMessage(messages.reply)} icon='reply' onClick={this.handleReply} />
+              <IconButton className='status__action-bar-button' title={intl.formatMessage(messages.reply)} icon='reply' iconComponent={ReplyIcon} onClick={this.handleReply} />
 
               <div className='status__action-bar-dropdown'>
                 <DropdownMenuContainer
@@ -186,6 +188,7 @@ class Conversation extends ImmutablePureComponent {
                   status={lastStatus}
                   items={menu}
                   icon='ellipsis-h'
+                  iconComponent={MoreHorizIcon}
                   size={18}
                   direction='right'
                   title={intl.formatMessage(messages.more)}

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

@@ -7,6 +7,8 @@ import { Helmet } from 'react-helmet';
 
 import { connect } from 'react-redux';
 
+import { ReactComponent as AlternateEmailIcon } from '@material-symbols/svg-600/outlined/alternate_email.svg';
+
 import { addColumn, removeColumn, moveColumn } from 'mastodon/actions/columns';
 import { mountConversations, unmountConversations, expandConversations } from 'mastodon/actions/conversations';
 import { connectDirectStream } from 'mastodon/actions/streaming';
@@ -81,6 +83,7 @@ class DirectTimeline extends PureComponent {
       <Column bindToDocument={!multiColumn} ref={this.setRef} label={intl.formatMessage(messages.title)}>
         <ColumnHeader
           icon='at'
+          iconComponent={AlternateEmailIcon}
           active={hasUnread}
           title={intl.formatMessage(messages.title)}
           onPin={this.handlePin}