Event export serializer

[tevoinea]

Summary of the Pull Request

What is this about?

This PR introduces a new JsonConverter for sending events. It closes #3076 and closes #3381.

Info on Pull Request

What does this include?

• A new feature flag EnableSlimEventSerialization which allows us to toggle the new behavior
• A new JsonConverter EventExportConverter
• Send 'slim' events to signalr queue and to webhooks queue
• Events logged to AppInsights are not slim (useful for debugging)
• Events stored in the events container are not slim (so that they can be retrieved in full capacity later via event id)
• Tests

Validation Steps Performed

How does someone test & validate?

• Unit tests for the JsonConverter
• Manual testing for receiving webhooks

[codecov-commenter]

Codecov Report

Merging #3543 (49c0c54) into main (e7b0dd5) will increase coverage by 0.07%. The diff coverage is 83.07%.

@@            Coverage Diff             @@
##             main    #3543      +/-   ##
==========================================
+ Coverage   38.97%   39.05%   +0.07%     
==========================================
  Files         301      302       +1     
  Lines       36848    36903      +55     
==========================================
+ Hits        14363    14413      +50     
- Misses      22485    22490       +5     

Files	Coverage Δ
...Service/ApiService/onefuzzlib/WebhookOperations.cs	37.43% <77.77%> (+1.72%)	:arrow_up:
...Service/ApiService/onefuzzlib/events/Converters.cs	91.66% <91.66%> (ø)
src/ApiService/ApiService/onefuzzlib/Events.cs	69.23% <37.50%> (-1.46%)	:arrow_down:

... and 4 files with indirect coverage changes