npm not found in CLI when npm is not installed

[talentlessguy]

Describe the bug
When I don't have npm installed, CLI throws an error

To Reproduce

1. Install CLI (using yarn / pnpm)
2. Try this:

$ proton-native init QuarkPlayer
Creating a new Proton Native app on /home/v1rtl/Coding/QuarkPlayer

Installing packages... This may take a few minutes. 

/bin/sh: npm: command not found

Expected behavior
CLI should fallback to pnpm and yarn if npm is not present

Versions:

• OS: Linux 5 x64
• Version: 2.0.4
• Node version 13.11.0

Additional context

There are other package managers than npm, two most popular are yarn and pnpm, so it is worth falling back to them in case npm is not in PATH (I use pnpm and don't have npm installed)