feat: move validate envoy gateway

[Xunzhuo]

What type of PR is this?

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #1992

[codecov]

Codecov Report

Merging #2024 (2be7255) into main (23c91a6) will increase coverage by 0.17%.
The diff coverage is 85.71%.

@@            Coverage Diff             @@
##             main    #2024      +/-   ##
==========================================
+ Coverage   65.55%   65.73%   +0.17%     
==========================================
  Files          92       93       +1     
  Lines       13509    13515       +6     
==========================================
+ Hits         8856     8884      +28     
+ Misses       4107     4089      -18     
+ Partials      546      542       -4     

Files	Coverage Δ
api/v1alpha1/validation/envoyproxy_validate.go	74.30% <ø> (ø)
internal/envoygateway/config/config.go	100.00% <100.00%> (+15.38%)	⬆️
api/v1alpha1/validation/envoygateway_validate.go	84.90% <84.90%> (ø)

... and 2 files with indirect coverage changes

[arkodg]

LGTM thanks !