Add @shlinkio/dashboard-server local package in src folder

[acelaya]

Closes #589

In order to be able to use all server domain code in production, for the react-router app, but also other entry points, this PR extracts that to its own meta-package, that is marked as external for vite and bundled individually.

That way, react-router's server bundle does not include that code, but instead just consume it as another external dependency.

Other entry points can do the same.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.94%. Comparing base (85bd190) to head (d1cf685).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #682   +/-   ##
========================================
  Coverage    76.94%   76.94%           
========================================
  Files           90       90           
  Lines          798      798           
  Branches        97       97           
========================================
  Hits           614      614           
  Misses          98       98           
  Partials        86       86           

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