ACC-270 [iOS] Fix labels and headings

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PR Submission Checklist for internal contributors

• The PR Title

  • [x] conforms to the style of semantic commits messages¹ supported in Wire's Github Workflow²
  • [x] contains a reference JIRA issue number like SQPIT-764
  • [x] answers the question: If merged, this PR will: ... ³

• The PR Description

  • [x] is free of optional paragraphs and you have filled the relevant parts to the best of your ability

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What's new in this PR?

In this PR, voice over issues have been fixed in:

• User profile screens (details, client list, device details),
• Account page,
• back buttons for each settings screen ( in accordance with accessibility requirements, we should specify the screen to which the user will go back)

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PR Post Submission Checklist for internal contributors (Optional)

• [x] Wire's Github Workflow has automatically linked the PR to a JIRA issue

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PR Post Merge Checklist for internal contributors

• [ ] If any soft of configuration variable was introduced by this PR, it has been added to the relevant documents and the CI jobs have been updated.

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References

1. https://sparkbox.com/foundry/semantic_commit_messages
2. https://github.com/wireapp/.github#usage
3. E.g. feat(conversation-list): Sort conversations by most emojis in the title #SQPIT-764.

Codecov Report

Merging #5858 (c1e2528) into develop (560ab15) will increase coverage by 0.05%. The diff coverage is 84.07%.

:exclamation: Current head c1e2528 differs from pull request most recent head 6b4e0d5. Consider uploading reports for the commit 6b4e0d5 to get more accurate results

@@             Coverage Diff             @@
##           develop    #5858      +/-   ##
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+ Coverage    60.58%   60.63%   +0.05%     
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  Files         1026     1026              
  Lines        57048    57152     +104     
  Branches     23686    23698      +12     
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+ Hits         34564    34656      +92     
- Misses       22108    22120      +12     
  Partials       376      376