🐛 Configure sccache for C++ coverage and linter builds

[denialhaag]

Description

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Configure the C and C++ compiler launchers for coverage and linter builds using the same sccache setup as the C++ test workflows. This enables caching for caller targets and prevents false failures in Verify sccache use when dependency builds do not use sccache.

Respect use-sccache-gha, and only enable the linter launchers when build-project is enabled.

AI notice

This PR and its contents were created with the assistance of GPT-6 Astra via Codex.

Checklist

• The pull request only contains commits that are focused and relevant to this change.
• I have added appropriate tests that cover the new/changed functionality.
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• The changes are fully tested and pass the CI checks.
• I have reviewed my own code changes.

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