Code Style & Performance Optimizations

[paescuj]

• Prefer object spread & slice for better readability and performance
• Disallow console.log statements via ESLint
• Speed up GitHub workflow by doing "Lint & Format" checks only once per run and using better NPM cache setup
• Speed up tests by using swc as transformer and for CLI tests
• Add some missing test cases
• Move Jest config to own file for better readability and validation
• Optimize NPM script for prettier

[coveralls]

Coverage increased (+1.5%) to 99.472% when pulling 988c59f on paescuj:optimizations into 0980e5b on open-cli-tools:main.