feat: Only fetching first level of dependencies

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

As stated in the docs and the source code this project always fetches all npm packages via the "npm ls" command. Therefore it is executed with "npm ls -all" (i left out the other parametes here for better understanding)

What i would like to have is an option to create the SBOM only with the packages listed in package.json file. Basically just the first level of dependencies.

## Describe the solution you'd like

Add an additional parameter e.g. "--only-first-level-dependencies" to call "npm ls" without the --depth parameter or set to 1 to fetch only the first level of dependencies/packages.

Default of the parameter can be false so it will by default fetch all dependencies and only if you are configuring it you can limit the fetching.

## Describe alternatives you've considered

none. i think this the nicest approach

## Additional context

Add any other context or screenshots about the feature request here.