accessibility related bugs with voiceover

Checklist

• I am reporting an issue in existing functionality that does not work as intended
• I've searched for existing GitHub issues

Description

In the issue #14 the voiceover accessibility was provided and that issue was closed, but unfortunately, the accessibility is still requiring too many adjustments in the iOS client.

1. Voiceover does not speak proper labels for many buttons in the interface, such as the "call" button, doesn't have any label and voiceover just said "button". A user could not identify the function of this button by this behaviour. Moreover, When we select the chats, the actions bar containing functions of "read, archive, delete" etc. are not readable. We cannot perform these functions on selected chats while using voiceover. These are just a few example of this kind of bugs with voiceover.
2. In a group conversation, we cannot open the group info screen to view it's members, or files, or set other options on a group.
3. When we select a chat in the main view, the voiceover does not indicate which chat is selected and which is not. It should speak "selected" with the marked items.
4. When we send a message, voiceover does not tell the status of the message whether is it being send, or its sent, or its delivered, or read/play by recipient. This information is very critical and should be presented to the voiceover users as it is for the sighted users.
5. lots of other focus related bugs are present, where the screen changes after pressing certain control, but voiceover curser does not render the newly appear content in gesture navigation. For example, if we want to change the notification tone, we couldn't focus to the available tones after selecting the responded option in the settings to choose from. Similarly, if we click on "compose" in the main windows, the newly popped up screen is not focused and rendered by accessibility service from where we can search for contact to start a new chat.
6. The share menu is not at all accessible when we try to share a link/file from other app like youtube.
7. Do read Comment1 By Simon818, Comment By Nick6489 and Comment2 By Simon818 for few more major accessibility bugs.

Expected Behavior

I've mentioned this along with the problems in above stated 4 points.

Steps to Reproduce

1. Install the latest client from apps store.
2. turn on voiceover and open telegram.
3. now, navigate around the program, the main view of conversation list, press "edit" button and select the chats, it will not tell you that it is now selected or not.
4. Then try to delete chats after selection, you'll not be able to focus to the action bar at bottum.
5. Open any conversation and try to find "call" button, you will not.
6. Open any group conversation and try to open "group info", you will not, with voiceover.
7. in the "chat info screen", try to navigate between "files, members, links or voice messages" view with voiceover, you can't do this.
8. in the main windows, simply try to start a new chat with "compose" button. You'll not be able to select/search contacts on that screen.
9. go to youtube, open a video, click "share" and choose telegram. You'll not be able to navigate within the telegram sharing screen here.

Environment

Device: iPhone/iPad X

iOS version: 13.X

App version: 7.X

Start by reproducing the reported flows with VoiceOver: chat selection, calling, group info, compose, message status, notification tones, and sharing from YouTube. Compare the accessibility behavior at each step with the expected behavior described in the issue; done requires defining and fixing a focused subset of these separate bugs rather than addressing the whole report at once.