Switch payload message collator depending on config

[fractalwrench]

Goal

Switches the payload message collator depending on config. This is not hooked up to the delivery service yet so won't affect production payloads.

Testing

Added unit tests.

[leandro-godon]

Lgtm

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.21%. Comparing base (3755a17) to head (5d911c5).

Additional details and impacted files

@@                 Coverage Diff                  @@
##           add-payload-flag     #561      +/-   ##
====================================================
- Coverage             80.22%   80.21%   -0.02%     
====================================================
  Files                   413      413              
  Lines                 11024    11027       +3     
  Branches               1619     1620       +1     
====================================================
+ Hits                   8844     8845       +1     
- Misses                 1532     1535       +3     
+ Partials                648      647       -1     

Files	Coverage Δ
...d/embracesdk/session/message/PayloadFactoryImpl.kt	93.02% <100.00%> (+0.25%)	⬆️

... and 2 files with indirect coverage changes