feat: add cross OS npm compatibility

[danisharora099]

ref to #273, adding a workflow that checks our builds against different OS enviornments would be helpful

[weboko]

I think it's bettor to scope this task to re-visiting packages and operations we use in js-waku and js-waku-examples:

• check if rm is cross-platform (usage of rimraf);
• check if env vars are set with cross-env;
• investigate npm commands for OS-specific operations;