Fix some icons names, unavailable in fontawesome5 (free license). (#8792)

- pencil => pencil-alt
- sliders => sliders-h

related: #8484 #8776

app/javascript/mastodon/components/column_header.js

@@ -126,7 +126,7 @@ class ColumnHeader extends React.PureComponent {
     }
 
     if (children || multiColumn) {
-      collapseButton = <button className={collapsibleButtonClassName} title={formatMessage(collapsed ? messages.show : messages.hide)} aria-label={formatMessage(collapsed ? messages.show : messages.hide)} aria-pressed={collapsed ? 'false' : 'true'} onClick={this.handleToggleClick}><i className='fa fa-sliders' /></button>;
+      collapseButton = <button className={collapsibleButtonClassName} title={formatMessage(collapsed ? messages.show : messages.hide)} aria-label={formatMessage(collapsed ? messages.show : messages.hide)} aria-pressed={collapsed ? 'false' : 'true'} onClick={this.handleToggleClick}><i className='fa fa-sliders-h' /></button>;
     }
 
     const hasTitle = icon && title;

app/javascript/mastodon/features/account/components/header.js

@@ -140,7 +140,7 @@ class Header extends ImmutablePureComponent {
     } else {
       actionBtn = (
         <div className='account--action-button'>
-          <IconButton size={26} icon='pencil' title={intl.formatMessage(messages.edit_profile)} onClick={this.openEditProfile} />
+          <IconButton size={26} icon='pencil-alt' title={intl.formatMessage(messages.edit_profile)} onClick={this.openEditProfile} />
         </div>
       );
     }

app/javascript/mastodon/features/list_timeline/index.js

@@ -150,7 +150,7 @@ class ListTimeline extends React.PureComponent {
         >
           <div className='column-header__links'>
             <button className='text-btn column-header__setting-btn' tabIndex='0' onClick={this.handleEditClick}>
-              <i className='fa fa-pencil' /> <FormattedMessage id='lists.edit' defaultMessage='Edit list' />
+              <i className='fa fa-pencil-alt' /> <FormattedMessage id='lists.edit' defaultMessage='Edit list' />
             </button>
 
             <button className='text-btn column-header__setting-btn' tabIndex='0' onClick={this.handleDeleteClick}>

app/javascript/mastodon/features/ui/components/columns_area.js

@@ -160,7 +160,7 @@ class ColumnsArea extends ImmutablePureComponent {
     this.pendingIndex = null;
 
     if (singleColumn) {
-      const floatingActionButton = shouldHideFAB(this.context.router.history.location.pathname) ? null : <Link key='floating-action-button' to='/statuses/new' className='floating-action-button' aria-label={intl.formatMessage(messages.publish)}><i className='fa fa-pencil' /></Link>;
+      const floatingActionButton = shouldHideFAB(this.context.router.history.location.pathname) ? null : <Link key='floating-action-button' to='/statuses/new' className='floating-action-button' aria-label={intl.formatMessage(messages.publish)}><i className='fa fa-pencil-alt' /></Link>;
 
       return columnIndex !== -1 ? [
         <ReactSwipeableViews key='content' index={columnIndex} onChangeIndex={this.handleSwipe} onTransitionEnd={this.handleAnimationEnd} animateTransitions={shouldAnimate} springConfig={{ duration: '400ms', delay: '0s', easeFunction: 'ease' }} style={{ height: '100%' }}>