Port libClangSharp to the LLVM 22 Clang AST

[tannergooding]

Note

This PR body was drafted by Copilot.

Updates sources/libClangSharp for the LLVM 21 -> 22 type-sugar refactor so the native library compiles and links against the 22.1.8 release (#779 bumped the tracked version ahead of the C++ port, leaving the regenerate-native legs red).

libClangSharp port

• ElaboratedType is removed; the elaboration keyword/qualifier and tag ownership moved onto TagType. clangsharp_Type_getOwnedTagDecl now uses TagType::isTagOwned()/getDecl(), and the Elaborated CXType kind mapping is dropped from CXType.cpp.
• InjectedClassNameType is now a TagType. The injected specialization is recovered via getCanonicalInjectedSpecializationType(ctx) (decl-level, the same replacement clang itself uses in findPartialSpecialization) and via getCanonicalTemplateSpecializationType(None, getTemplateName(ctx), getTemplateArgs(ctx)) (type-level, matching clang's own ClassTemplatePartialSpecializationDecl::getCanonicalInjectedSpecializationType construction).
• DependentTemplateSpecializationType is folded into TemplateSpecializationType; its template-argument branch is dropped and handled by the existing TemplateSpecializationType branch.
• UsingType::getFoundDecl -> getDecl (same underlying UsingShadowDecl).

One inherent behavior shift: the injected-specialization getters now return the canonical injected type -- LLVM 22 no longer stores the as-written one. Same template and injected args.

Build

• CMakeLists.txt: set CMAKE_MSVC_RUNTIME_LIBRARY to the static CRT (/MT) so libClangSharp links against the official /MT LLVM release binaries without LNK2038. Bumped cmake_minimum_required 3.13 -> 3.15 so the runtime-library policy applies. Validated locally: compiles with 0 errors and links libClangSharp.dll against the real 22.1.8 release via a plain -DPATH_TO_LLVM invocation.

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Detect refactor

Moves the regenerate-native change-detection and package-version verification out of YAML into build.ps1/build.sh (--detectchanges/--verifypackages) so they're reproducible and testable locally, and thins the workflow down to glue around the scripts.

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Directory.Packages.props intentionally stays on the 21.1.8 consuming refs so ci.yml restore stays green -- the 22.1.8 native packages are published by this workflow first. A stacked follow-up then bumps the consuming refs, regenerates the managed bindings, and fixes the CX_TypeClass ordinals (the LLVM 22 TypeNodes change removes Elaborated/DependentTemplateSpecialization and reparents InjectedClassName, shifting the ordinals that clangsharp_Type_getTypeClass feeds into the managed enum).