feat: batching events and webhook plugin support

[EnriqueL8]

Enable batching for subscriptions

• Write more robust tests to match coverage
• Handle the firstData for events and decide what we do there
• Refactor the webhook plugin to make it more modular instead of copying code across functions

[codecov-commenter]

Codecov Report

Merging #1359 (be50b97) into main (816463c) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##             main    #1359    +/-   ##
========================================
  Coverage   99.98%   99.98%            
========================================
  Files         315      315            
  Lines       21907    22036   +129     
========================================
+ Hits        21903    22032   +129     
  Misses          2        2            
  Partials        2        2            

Impacted Files	Coverage Δ
pkg/core/event.go	100.00% <ø> (ø)
pkg/core/subscription.go	100.00% <ø> (ø)
internal/events/event_dispatcher.go	100.00% <100.00%> (ø)
internal/events/event_manager.go	100.00% <100.00%> (ø)
internal/events/subscription_manager.go	100.00% <100.00%> (ø)
internal/events/system/events.go	100.00% <100.00%> (ø)
internal/events/webhooks/webhooks.go	100.00% <100.00%> (ø)
internal/events/websockets/websockets.go	100.00% <100.00%> (ø)
internal/orchestrator/subscriptions.go	100.00% <100.00%> (ø)

[EnriqueL8]

PR not ready for review as I need to work on removing the nack I added and test the infinite retry is now working

[peterbroadhurst]

@EnriqueL8 - looked great - I've filled in a couple of commits to simplify a bit of duplicate logic, and found an efficiency in deferring parsing of some data from string to JSON.

Also made the change to prevent creation of subscriptions with batching enabled, for event transports that don't support it.

[peterbroadhurst]

Popped back to draft as there's a potential issue with creating subscriptions with the default transport

[EnriqueL8]

Tested the above fix from Peter and all good you can create a subscription with a transport and it defaults to web hooks