feat(apps): add IPostSystemMessageSent event

[Gustrb]

Proposed changes (including videos or screenshots)

Currently, there is no way to run an app when a given system message is sent, since we only trigger the IPostMessageSent for normal messages.
We could have followed the approach of having system messages also trigger the event, but that would create a pain point, since we would not be able to add the methods to check (to block messages).
This Pull Request, introduces the new event that is triggered on system messages, so the apps can respond to it

Issue(s)

Steps to test or reproduce

Further comments

CONN-482

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🦋 Changeset detected

Latest commit: bd3d4a3

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 36 packages

Name	Type
@rocket.chat/meteor	Minor
@rocket.chat/apps-engine	Minor
@rocket.chat/apps	Minor
@rocket.chat/core-services	Patch
@rocket.chat/core-typings	Minor
@rocket.chat/fuselage-ui-kit	Major
@rocket.chat/rest-typings	Minor
@rocket.chat/ddp-streamer	Patch
@rocket.chat/presence	Patch
rocketchat-services	Patch
@rocket.chat/uikit-playground	Patch
@rocket.chat/api-client	Patch
@rocket.chat/cron	Patch
@rocket.chat/ddp-client	Patch
@rocket.chat/freeswitch	Patch
@rocket.chat/gazzodown	Major
@rocket.chat/livechat	Patch
@rocket.chat/model-typings	Patch
@rocket.chat/ui-contexts	Major
@rocket.chat/account-service	Patch
@rocket.chat/authorization-service	Patch
@rocket.chat/omnichannel-transcript	Patch
@rocket.chat/presence-service	Patch
@rocket.chat/queue-worker	Patch
@rocket.chat/stream-hub-service	Patch
@rocket.chat/license	Patch
@rocket.chat/omnichannel-services	Patch
@rocket.chat/pdf-worker	Patch
@rocket.chat/models	Patch
@rocket.chat/network-broker	Patch
@rocket.chat/ui-avatar	Major
@rocket.chat/ui-client	Major
@rocket.chat/ui-video-conf	Major
@rocket.chat/ui-voip	Major
@rocket.chat/web-ui-registration	Major
@rocket.chat/instance-status	Patch

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.44%. Comparing base (b9e7e38) to head (bd3d4a3).
Report is 1 commits behind head on develop.

Additional details and impacted files

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  Lines        68163    68163           
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  Hits         40517    40517           
  Misses       24990    24990           
  Partials      2656     2656           

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