fix: added namespace support and improved testing

.gitignore

Gemfile

Gemfile.lock

README.md

lib/generators/nexus_cqrs/command_generator.rb

lib/generators/nexus_cqrs/query_generator.rb

lib/nexus_cqrs/base_command_handler.rb

lib/nexus_cqrs/base_query_handler.rb

lib/nexus_cqrs/command_executor.rb

lib/nexus_cqrs/version.rb

spec/lib/generators/command_generator_spec.rb

spec/lib/generators/query_generator_spec.rb