Make license-ls compatible with npm 7.x

[sch0rsch]

This fixes issue #20

• do not pass --csv-option to npm list and make license-ls compatible with npm 7.x
• handle errors and stop the spinner so that the program terminates
• small refactorings

[thefurdui]

@morficus, please, review

[dotcs]

@sch0rsch I found that changes in this PR not replicate the previous behavior. It only lists direct dependencies - even without configuring --depth 0. See the docs for npm list which since v7 state that

This command will print to stdout all the versions of packages that are installed, as well as their dependencies when --all is specified, in a tree structure.

So I think an additional --all is required. I've implemented this in a bugfix branch in my own fork.

Additional note for those that wait on @morficus merging this PR: In the meantime, you can use npx capabilities to run from a GitHub repository branch directly. To run the changes in this PR run npx --yes sch0rsch/license-ls#make-compatible-with-npm-7 or use npx --yes dotcs/license-ls#npm-7+ which includes the fix mentioned above.

[robross0606]

Two years and this still hasn't been resolved.