fix: handle missing latest tag during version check

[mcous]

Overview

This PR makes two changes to how the calls to npm view and npm publish are made:

1. If npm view package-name comes back empty due to [BUG] npm view package@latest exits with code 0 and no output if latest tag does not exist npm/cli#6408, we will now retry with npm view package-name@tag, to try to get some information
2. If npm publish fails because the requested version already exists, the action will not fail.

Fixes #89

Change details

• Restructured how the npmPublish function is broken up to delegate to a new compareAndPublish function
  • This change means only one temporary .npmrc file is created, rather than two
• Renamed and reorganized some things for consistency