chore(ci): introduce caching around npm install step

[thisislawatts]

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What does this PR do?

Reduce run time for prepare-build by 10-15 seconds, this job has a p95 of 4m 4s over the last 30 days. What makes this change worthwhile is that this job is the bottleneck before we fan out to our platform specific processes.

• Introduces dependency caching around npm for the prepare-build
• Adopt a few flags for npm ci aimed at improving performance of command
  • --no-audit: Skipping the audit check can save time during the installation process because npm won't spend resources analyzing packages for security vulnerabilities. We already have leading security tool snyk integrated elsewhere in our build pipeline ;)
  • --no-progress: Disabling the progress bar can slightly improve performance by reducing the overhead of updating and rendering progress information in the terminal. This improvement may be more noticeable in automated or CI/CD (Continuous Integration/Continuous Deployment) environments where visual feedback is less critical.
  • --cache .npm: Specifying a cache directory (--cache) allows us to reliably cache this with CircleCI
  • --prefer-offline: This option can also boost performance, particularly in scenarios where network connectivity is unreliable or slow. By preferring offline packages, npm first looks for cached packages in the local cache directory (./npm) or any previously downloaded packages, reducing the need for network requests during installation.