feat(mutate): minimize unmarshals

[KhaledEmaraDev]

Explanation

Minimize the number of times we have to unmarshal within mutate policies.

Related issue

Milestone of this PR

Documentation (required for features)

My PR contains new or altered behavior to Kyverno.

• I have sent the draft PR to add or update the documentation and the link is:

What type of PR is this

Proposed Changes

Proof Manifests

Checklist

• I have read the contributing guidelines.
• I have read the PR documentation guide and followed the process including adding proof manifests to this PR.
• This is a bug fix and I have added unit tests that prove my fix is effective.
• This is a feature and I have added CLI tests that are applicable.
• My PR needs to be cherry picked to a specific release branch which is .
• My PR contains new or altered behavior to Kyverno and
  • CLI support should be added and my PR doesn't contain that functionality.

Further Comments

[codecov]

Codecov Report

Attention: Patch coverage is 38.88889% with 11 lines in your changes missing coverage. Please review.

Project coverage is 11.66%. Comparing base (6e73e85) to head (5062610).

Files	Patch %	Lines
api/kyverno/v1/common_types.go	0.00%	4 Missing ⚠️
pkg/engine/mutate/mutation.go	70.00%	2 Missing and 1 partial ⚠️
api/kyverno/v1/zz_generated.deepcopy.go	0.00%	1 Missing ⚠️
.../applyconfigurations/kyverno/v1/foreachmutation.go	0.00%	1 Missing ⚠️
pkg/engine/handlers/mutation/common.go	0.00%	1 Missing ⚠️
pkg/policy/mutate/validate.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10702      +/-   ##
==========================================
+ Coverage   11.64%   11.66%   +0.01%     
==========================================
  Files         933      933              
  Lines       85285    85281       -4     
==========================================
+ Hits         9933     9945      +12     
+ Misses      74223    74203      -20     
- Partials     1129     1133       +4     

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