Deprecate `plugins` command

Is your feature request related to a problem? Please describe.

No response

Describe the solution you'd like

To simplify, per discussion with @rigor789 in Discord.

Describe alternatives you've considered

Devs can use their package manager directly to install plugins: npm install <foo>, etc.

Anything else?

I'd suggest any reference to ns plugin install in docs be changed to only mention NPM's install command: "npm install <foo> or as appropriate for your package manager", to reduce docs maintenance. Users of other package managers know the analogous command for their package manager.

Please accept these terms

• I have searched the existing issues as well as StackOverflow and this has not been posted before
• I agree to follow this project's Code of Conduct

Comece localizando a implementação do comando plugins e todas as referências na documentação a ns plugin install; a issue não fornece caminhos de arquivos nem de testes. Confirme o comportamento de descontinuação pretendido pelo projeto, atualize as referências para usar a terminologia do gerenciador de pacotes e verifique se o comando e a documentação refletem a decisão de forma consistente.