chore: cleanup nx.json and remove unnecessary .gitkeep files

[Phillip9587]

• removed generator defaults for the deprecated @nrwl/schematics from nx.json
• removed not existing style option from @nrwl/library
• deleted unnecessary .gitkeep files

[nx-cloud]

☁️ Nx Cloud Report

CI ran the following commands for commit 2f2a4ee. Click to see the status, the terminal output, and the build insights.

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✅ Successfully ran 3 targets

• nx run-many --all --parallel --target=build --max-parallel=3
• nx run-many --all --parallel --target=test --max-parallel=3
• nx run-many --all --parallel --target=lint --max-parallel=3

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