Move tsx to main dependencies; don't run superfluous code quality workflow setup steps

[cmenon12]

Description

• Move the tsx dependency to the main dependencies, to avoid issues with Docker not finding tsx.
• If there's a cache hit in the setup job of the code quality workflow, don't download it and don't run the rest of the steps.

Related issues: none

Checklist before marking as ready for review

Before marking as ready for review, please check that you have:

• Added appropriate and passing tests for the changes I made.
• Not broken any existing functionality or tests.
• Not introduced any new linting or formatting errors.
• Only added new dependencies that are necessary, do not introduce security vulnerabilities, and with tilde (~) version ranges.
• Checked and resolved UI accessibility issues using Axe devtools. Unresolved issues are described above.
• Updated the documentation if necessary.

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