Add Gin <-> Arpc integration example leveraging webchat

[KevM]

Closes #62

I took a swing at modifying the existing chat example to be hosted by Gin and add a simple web API exposing the room user identifiers via GET /room

Let me know what you think. I wasn't sure you wanted a dependency on Gin, so I made the example folder it's own go module. If you know a better way, I am happy to oblige.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 57.11%. Comparing base (802970d) to head (6933ab8).
Report is 31 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #63      +/-   ##
==========================================
- Coverage   64.34%   57.11%   -7.24%     
==========================================
  Files           6        7       +1     
  Lines        1666     1884     +218     
==========================================
+ Hits         1072     1076       +4     
- Misses        550      762     +212     
- Partials       44       46       +2     

Flag	Coverage Δ
unittests	57.11% <ø> (-7.24%)	⬇️

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[lesismal]

arpc core implementation imports std only,the arpc/go.mod only declares the package name but doesn't run go mod tidy to keep the core clean and zero dependencies.
So, please don't generate go.mod and go.sum.

Please don't use too many 3rd libs if not needed, don't commit bin files:

[lesismal]

I'll close this pr cause the bin file has been in this branch's commit history, reset or re-fork a clean branch will be better.

[KevM]

I'm not sure what to do. The example requires Gin. I'll let you do what you want with this.

[lesismal]

ok, I'll do it, tks bro!