Add support for `watch` flag in `import` command

[Harsh4902]

Reason/Context

• We can extend the functionality of import command by adding --watch flag.
• It allows users to create importer job for local files from CLI.

Description

• We had a use case suggest by @driccio, that Microcks should allow users to create an importer job for local files as well here.

• In microcks-cli we can easily add --watch flag which tells CLI to keep watch on a particular file which is imported to Microcks using import command. And on change event it will be automatically re-imported by CLI.

• For example: import samples/weather-forecast-openapi.yml --watch

Implementation ideas

See https://medium.com/@skdomino/watch-this-file-watching-in-go-5b5a247cf71f for inspiration on how to do this.