Add type to the message sent by the sender subsystem

[avillega]

In order for the SDKs to correctly identify if the message it is getting
is a notify, invoke or resume.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 22 lines in your changes missing coverage. Please review.

Project coverage is 54.83%. Comparing base (de5339e) to head (84b7b23).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/app/subsystems/aio/sender/sender.go	0.00%	22 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #535      +/-   ##
==========================================
- Coverage   54.96%   54.83%   -0.14%     
==========================================
  Files         129      129              
  Lines       13906    13919      +13     
==========================================
- Hits         7644     7632      -12     
- Misses       5806     5830      +24     
- Partials      456      457       +1     

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