Improve participants button aria-label for screen reader users

[ahmadkadri]

Description: In the participant button in the toolbar the number of participants is displayed but it is not accessed for the screen reader users.

Actual Behavior: The screen reader read just the word open participants pane.

Expected Behavior: The number of participants should also be provided for screen reader users.

Before:

withoutParticipantsCount.mp4

After:

ParticipantsCount.mp4

issue jitsi community: https://community.jitsi.org/t/accessibility-improvement/133102

[jitsi-jenkins]

Hi, thanks for your contribution!
If you haven't already done so, could you please make sure you sign our CLA (https://jitsi.org/icla for individuals and https://jitsi.org/ccla for corporations)? We would unfortunately be unable to merge your patch unless we have that piece :(.

[Calinteodor]

@ahmadkadri Thank you for your contribution! Can you please fix the linter issues?

[Calinteodor]

Jenkins please test this please!

[Calinteodor]

@ahmadkadri There are some failing tests related to your changes.

You must fork and create here https://github.com/jitsi/jitsi-meet-torture a branch with the same name as this one, check the tests that are failing by running this command

mvn clean test
-DforkCount=0
-Djitsi-meet.instance.url="https://localhost:8080/"
-Dtest.report.directory=target/chrome-2-chrome
-Djitsi-meet.tests.toRun=TEST_NAME

[damencho]

Jenkins test this please.

[ahmadkadri]

@damencho we had tow kind of failed tests on open and on close. i improve the code so we still have to fix on open in the test (we work on it).