enhancement: add api-version for load

[shawnh2]

What type of PR is this?

What this PR does / why we need it:

• Add support for ReferenceGrant in load
• Add APIVersion field for each loaded resources

This is needed for #5767

Which issue(s) this PR fixes:

Release Notes: Yes/No

[arkodg]

LGTM thanks !

[codecov]

Codecov Report

Attention: Patch coverage is 82.05128% with 14 lines in your changes missing coverage. Please review.

Project coverage is 65.21%. Comparing base (096cb8d) to head (9bf5e82).
Report is 41 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/gatewayapi/resource/load.go	82.05%	14 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5816      +/-   ##
==========================================
+ Coverage   65.19%   65.21%   +0.01%     
==========================================
  Files         214      219       +5     
  Lines       34321    34918     +597     
==========================================
+ Hits        22377    22773     +396     
- Misses      10591    10761     +170     
- Partials     1353     1384      +31     

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