nrdk greetings command

[cvarjao]

As a Developer I need to understand how to add commands to nrdk so that I can understand how nrdk works and effectively contribute to the project

DoD:

• create the greetings command by running npm run oclif -- greetings
• npx @bcgov/nrdk greetings should output 'Hello World'
• npx @bcgov/nrdk greetings Earth should output 'Hello Earth'
• Be able to put a breakpoint and inspect what is going to be printed before printing
• Have unit tests valid and passing by running npm run mocha -- "test/**/<greeetings>.test.ts"

Reference:

• https://oclif.io/docs/generator_commands#oclif-command-name
• https://oclif.io/docs/testing