feat: generic webhook receiver

[fuskovic]

Closes: #4486

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[codecov]

Codecov Report

❌ Patch coverage is 76.62835% with 61 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.12%. Comparing base (60fba34) to head (097f65b).
⚠️ Report is 30 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/webhook/kubernetes/external/validation.go	0.00%	33 Missing ⚠️
pkg/webhook/external/generic.go	76.69%	23 Missing and 1 partial ⚠️
pkg/webhook/external/refresh.go	90.24%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5305      +/-   ##
==========================================
+ Coverage   55.98%   56.12%   +0.14%     
==========================================
  Files         405      409       +4     
  Lines       29858    30189     +331     
==========================================
+ Hits        16715    16945     +230     
- Misses      12177    12271      +94     
- Partials      966      973       +7     

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