[MA-29]: Add appropriate name information (#29694)

Co-authored-by: Mattermost Build <build@mattermost.com>

webapp/channels/src/components/post_priority/post_priority_picker.tsx

@@ -132,7 +132,10 @@ function PostPriorityPicker({
 
     return (
         <Picker className='PostPriorityPicker'>
-            <Header className='modal-title'>
+            <Header
+                className='modal-title'
+                id='messagePriority-heading'
+            >
                 {formatMessage({
                     id: 'post_priority.picker.header',
                     defaultMessage: 'Message priority',

webapp/channels/src/components/post_priority/post_priority_picker_overlay.tsx

@@ -121,6 +121,7 @@ function PostPriorityPickerOverlay({
                                 zIndex: 3,
                             }}
                             {...getPickerFloatingProps()}
+                            aria-labelledby='messagePriority-heading'
                         >
                             <PostPriorityPicker
                                 settings={settings}