Support dispatcher format for triggers

[Cali0707]

Fixes #8077

Proposed Changes

• Add delivery format to the trigger CRD
• Use the trigger format when sending to the trigger subscriber

Pre-review Checklist

• At least 80% unit test coverage
• E2E tests for any new behavior
• Docs PR for any user-facing impact
• Spec PR for any new API feature
• Conformance test for any change to the spec

Release Note

Triggers referencing MTChannelBased Brokers now support the Delivery Format option

[Cali0707]

/cc @creydr

One question I had here is should we also use the delivery format when delivering to the DLS?

[codecov]

Codecov Report

Attention: Patch coverage is 42.85714% with 4 lines in your changes missing coverage. Please review.

Project coverage is 67.44%. Comparing base (bf945f9) to head (4eba0b5).
Report is 4 commits behind head on main.

Files	Patch %	Lines
pkg/broker/filter/filter_handler.go	42.85%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##           main    #8151       +/-   ##
=========================================
+ Coverage      0   67.44%   +67.44%     
=========================================
  Files         0      371      +371     
  Lines         0    18006    +18006     
=========================================
+ Hits          0    12145    +12145     
- Misses        0     5087     +5087     
- Partials      0      774      +774     

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[Cali0707]

/cc @pierDipi @creydr

This should be ready for review & has an e2e test now

[Cali0707]

/test upgrade-tests

[pierDipi]

/lgtm
/approve

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Cali0707, pierDipi

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