Add pnpm-config command

[attiasas]

• All tests have passed. If this feature is not already covered by the tests, new tests have been added.
• The pull request is targeting the dev branch.
• The code has been validated to compile successfully by running go vet ./....
• The code has been formatted properly using go fmt ./....

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Add pnpm-config command to create a configurations for pnpm to used in audit at jfrog/jfrog-cli-security#18.
Depends on:
jfrog/jfrog-cli-core#1132