chore: simplify build and workflows

[tbouffard]

• Use a more convenient name for the npm script that does TS compilation
• Keep a single build demo npm script for simplificty
• Use the bahmutov/npm-install action to manage cache and dependencies install

Notes

First implemented in https://github.com/process-analytics/bonita-day-demo-2023/pull/7

[github-actions[bot]]

:recycle: PR Preview b51d7ced8c757d659af8f1bbef00e3ddf22578a6 has been successfully destroyed since this PR has been closed.

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