refactor: mv help to briefing, feat cp file to set up project src

plugins/deadlock-extension/package.json

plugins/deadlock-extension/src/command.ts

plugins/deadlock-extension/src/deadlockPanel.ts

plugins/deadlock-extension/src/extension.ts

plugins/deadlock-extension/src/view/briefingView.ts

plugins/deadlock-extension/src/view/helpView.ts