[MM-61633]: Add aria-label in the on-boarding button (#29812)

* MM-61633: Add aria-label in the onboarding button

* MM-61633: Update formatting

* MM-61633: Add strings for localization

---------

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

webapp/channels/src/components/onboarding_tasklist/onboarding_tasklist.tsx

@@ -2,7 +2,7 @@
 // See LICENSE.txt for license information.
 
 import React, {useRef, useCallback, useEffect, useState} from 'react';
-import {FormattedMessage} from 'react-intl';
+import {FormattedMessage, useIntl} from 'react-intl';
 import {useDispatch, useSelector} from 'react-redux';
 import styled, {css} from 'styled-components';
 
@@ -126,6 +126,7 @@ const Button = styled.button<{open: boolean}>(({open}) => {
 });
 
 const OnBoardingTaskList = (): JSX.Element | null => {
+    const {formatMessage} = useIntl();
     const hasPreferences = useSelector((state: GlobalState) => Object.keys(getMyPreferencesSelector(state)).length !== 0);
 
     useEffect(() => {
@@ -255,6 +256,7 @@ const OnBoardingTaskList = (): JSX.Element | null => {
                 ref={trigger}
                 open={open}
                 data-cy='onboarding-task-list-action-button'
+                aria-label={formatMessage({id: 'onboardingTask.checklist.start_onboarding_process', defaultMessage: 'Start the onboarding process.'})}
             >
                 {open ? <CloseIcon size={20}/> : <PlaylistCheckIcon size={20}/>}
                 {itemsLeft !== 0 && (<span>{itemsLeft}</span>)}

webapp/channels/src/i18n/en.json

@@ -4570,6 +4570,7 @@
   "onboardingTask.checklist.main_subtitle": "Let's get up and running.",
   "onboardingTask.checklist.no_thanks": "No, thanks",
   "onboardingTask.checklist.start_enterprise_now": "Start your free Enterprise trial now!",
+  "onboardingTask.checklist.start_onboarding_process": "Start the onboarding process.",
   "onboardingTask.checklist.task_complete_your_profile": "Complete your profile.",
   "onboardingTask.checklist.task_download_mm_apps": "Download the Desktop and Mobile Apps.",
   "onboardingTask.checklist.task_invite_team_members": "Invite team members to the workspace.",