Add Fetch and Size methods on samplers and storage textures

[ArthurVasseur]

This MR adds texel fetching and texture size queries to NZSL, as new methods on samplers and storage textures.

Method	Available on	Signature	GLSL	SPIR-V
Fetch	Samplers, except depth samplers and cubemaps	Fetch(coords: vecN[i32], lod: i32) -> vec4[T]	texelFetch	OpImage + OpImageFetch (Lod operand)
Size	Samplers	Size(lod: i32) -> i32 / vecN[i32]	textureSize	OpImage + OpImageQuerySizeLod
Size	Storage textures	Size() -> i32 / vecN[i32]	imageSize	OpImageQuerySize

Type returned by Size:

• i32 for 1D images
• vec2[i32] for 1D arrays, 2D images and cubemaps
• vec3[i32] for 2D arrays and 3D images

[codecov]

Codecov Report

❌ Patch coverage is 89.52880% with 20 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.73%. Comparing base (e080108) to head (3965fea).

Files with missing lines	Patch %	Lines
...NZSL/Ast/Transformations/ValidationTransformer.cpp	70.00%	9 Missing ⚠️
src/NZSL/Ast/Utils.cpp	73.07%	7 Missing ⚠️
src/NZSL/SpirV/SpirvAstVisitor.cpp	93.47%	3 Missing ⚠️
src/NZSL/GlslWriter.cpp	93.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #103      +/-   ##
==========================================
+ Coverage   76.56%   76.73%   +0.16%     
==========================================
  Files         208      208              
  Lines       26342    26530     +188     
  Branches     8090     8036      -54     
==========================================
+ Hits        20170    20357     +187     
+ Misses       6056     6048       -8     
- Partials      116      125       +9     

Files with missing lines	Coverage Δ
include/NZSL/SpirV/SpirvAstVisitor.hpp	100.00% <ø> (ø)
...Transformations/ConstantPropagationTransformer.cpp	69.86% <ø> (ø)
...rc/NZSL/Ast/Transformations/LiteralTransformer.cpp	81.18% <100.00%> (+0.21%)	⬆️
...rc/NZSL/Ast/Transformations/ResolveTransformer.cpp	83.70% <100.00%> (+0.06%)	⬆️
src/NZSL/LangWriter.cpp	88.39% <100.00%> (+0.20%)	⬆️
tests/src/Tests/ComputeTests.cpp	100.00% <100.00%> (ø)
tests/src/Tests/ErrorsTests.cpp	100.00% <ø> (ø)
tests/src/Tests/IdentifierTests.cpp	100.00% <100.00%> (ø)
src/NZSL/GlslWriter.cpp	84.22% <93.33%> (+0.12%)	⬆️
src/NZSL/SpirV/SpirvAstVisitor.cpp	84.75% <93.47%> (+0.35%)	⬆️
... and 2 more

... and 7 files with indirect coverage changes

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[SirLynix]

LGTM