[WIP] Initial implementation of an EventHandler

[r-marques]

This pr is an initial tentative implementation of a backend event handler so that producer processes can emit events and a consumer process can read the events.

This pr contains some boiler plate code that is not really needed at this point but the idea was to abstract all the aspects of events handling so that it can be easy to extend.

[codecov-io]

Codecov Report

Merging #1347 into events-api-first-cut will decrease coverage by 1.06%.
The diff coverage is 66.66%.

@@                   Coverage Diff                    @@
##           events-api-first-cut    #1347      +/-   ##
========================================================
- Coverage                 98.19%   97.13%   -1.07%     
========================================================
  Files                        54       57       +3     
  Lines                      2443     2831     +388     
========================================================
+ Hits                       2399     2750     +351     
- Misses                       44       81      +37

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