Adds publish/share/refCount operators and respective tests

[christophstrasen]

Adds three familiar Rx operators:

• publish: make a cold observable connectable
• refCount: auto connect/disconnect based on subscribers
• share: publish()->refCount() sugar

I lean on these in LQR to fan out streams without resubscribing upstream. Figured they belong in core so others can use the same patterns. Tests included and wired into the operator suite but I lack the travisCI setup to run them so apologies if something fails.

Mad props to you for the work on lua-reactivex :)

[4O4]

Hi, thank you for your contribution 🎉 I will review it in the upcoming days

[christophstrasen]

Appreciated :).

And FYI on the main branch I maintain a more "radical" change for compatibibility with more restrictive lua environments but that may be a bridge too far to upstream so I did not make a PR for that. https://github.com/christophstrasen/lua-reactivex/tree/main

Cheers

[4O4]

Oh that's neat! Actually I would be okay with integrating more platform-specific changes as long as we can keep compatibility for different platforms. My own usage was also always outside of Love2D scope, but I always postponed adding more information about it 🙈