add new features to the config file

[hector-js]

Is your feature request related to a problem? Please describe.
given a .hjs.config.json property file already created, when the user wants to add or overwrite a new property, it should be able to do it with the command and not to overwrite the file.

Describe the solution you'd like
given the following .hjs.config.json file:

{
  "logs": "tiny",
}

when I execute the next command hjs config --port 8080, the file will be updated like:

{
  "logs":"tiny",
  "port":8080
}