Change icons in web UI (#27385)

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

app/javascript/mastodon/features/compose/components/upload_button.jsx

@@ -6,6 +6,8 @@ import ImmutablePropTypes from 'react-immutable-proptypes';
 import ImmutablePureComponent from 'react-immutable-pure-component';
 import { connect } from 'react-redux';
 
+import { ReactComponent as AddPhotoAlternateIcon } from '@material-symbols/svg-600/outlined/add_photo_alternate.svg';
+
 import { IconButton } from '../../../components/icon_button';
 
 const messages = defineMessages({
@@ -62,7 +64,7 @@ class UploadButton extends ImmutablePureComponent {
 
     return (
       <div className='compose-form__upload-button'>
-        <IconButton icon='paperclip' title={message} disabled={disabled} onClick={this.handleClick} className='compose-form__upload-button-icon' size={18} inverted style={iconStyle} />
+        <IconButton icon='paperclip' iconComponent={AddPhotoAlternateIcon} title={message} disabled={disabled} onClick={this.handleClick} className='compose-form__upload-button-icon' size={18} inverted style={iconStyle} />
         <label>
           <span style={{ display: 'none' }}>{message}</span>
           <input