add kref uid as available template field

[lionelvillard]

Fixes #5769

Proposed Changes

• 🎁 Add UID to the available Kreference mapping resolver template field

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

:gift: Add UID to the available Kreference mapping resolver template field 

Docs

[pierDipi]

/lgtm

[codecov]

Codecov Report

Merging #5810 (84e98ff) into main (fcf6738) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #5810   +/-   ##
=======================================
  Coverage   82.39%   82.40%           
=======================================
  Files         204      204           
  Lines        6454     6455    +1     
=======================================
+ Hits         5318     5319    +1     
  Misses        778      778           
  Partials      358      358           

Impacted Files	Coverage Δ
pkg/resolver/mapping_resolver.go	73.46% <100.00%> (+0.55%)	⬆️

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[pierDipi]

@lionelvillard you need to run update-codegen.sh to update the CM sha.

[pierDipi]

/lgtm

[knative-prow-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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[duglin]

thanks!