Add --slug option to plugin/theme install for custom directory naming#506

Copilot wants to merge 2 commits intomainwp-cli/extension-command:mainfrom

copilot/fix-1570774-87201472-127cd70a-3a52-471a-9dc4-fc27ebad98fcwp-cli/extension-command:copilot/fix-1570774-87201472-127cd70a-3a52-471a-9dc4-fc27ebad98fcCopy head branch name to clipboard