Add shellcheck to quality checks

[hughns]

Type of change

• Feature
• Bugfix
• Technical
• Other :

Content

Motivation and context

Screenshots / GIFs

Tests

• Step 1
• Step 2
• Step ...

Tested devices

• Physical
• Emulator
• OS version(s):

Checklist

• Changes have been tested on an Android device or Android emulator with API 23
• UI change has been tested on both light and dark themes
• Accessibility has been taken into account. See https://github.com/element-hq/element-x-android/blob/develop/CONTRIBUTING.md#accessibility
• Pull request is based on the develop branch
• Pull request includes a new file under ./changelog.d. See https://github.com/element-hq/element-x-android/blob/develop/CONTRIBUTING.md#changelog
• Pull request includes screenshots or videos if containing UI changes
• Pull request includes a sign off
• You've made a self review of your PR

[github-actions]

Thank you for your contribution! Here are a few things to check in the PR to ensure it's reviewed as quickly as possible:

• Your branch should be based on origin/develop, at least when it was created.
• There is a changelog entry in the changelog.d folder with the Towncrier format.
• The test pass locally running ./gradlew test.
• The code quality check suite pass locally running ./gradlew runQualityChecks.
• If you modified anything related to the UI, including previews, you'll have to run the Record screenshots GH action in your forked repo: that will generate compatible new screenshots. However, given Github Actions limitations, it will prevent the CI from running temporarily, until you upload a new commit after that one. To do so, just pull the latest changes and push an empty commit.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.41%. Comparing base (e9c262e) to head (6c1fb4f).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #2781   +/-   ##
========================================
  Coverage    73.41%   73.41%           
========================================
  Files         1523     1523           
  Lines        36528    36528           
  Branches      7038     7038           
========================================
  Hits         26816    26816           
  Misses        6043     6043           
  Partials      3669     3669           

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[bmarty]

Thanks for starting to work on this @hughns, do you intend to finish it? Else please let me know, I can do it.

[hughns]

@bmarty I don't have any plans to progress this at the moment. So, if you can take it over then great 👍 thank you.