[NFC] Move DeclID from serialization/ASTBitCodes.h to AST/DeclID.h (#89873)

Previously, the DeclID is defined in serialization/ASTBitCodes.h under
clang::serialization namespace. However, actually the DeclID is not
purely used in serialization part. The DeclID is already widely used in
AST and all around the clang project via classes like `LazyPtrDecl` or
calling `ExternalASTSource::getExernalDecl()`. All such uses are via the
raw underlying type of `DeclID` as `uint32_t`. This is not pretty good.

This patch moves the DeclID class family to a new header `AST/DeclID.h`
so that the whole project can use the wrapped class `DeclID`,
`GlobalDeclID` and `LocalDeclID` instead of the raw underlying type.
This can improve the readability and the type safety.

1 files changed, 2 insertions, 2 deletions

diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 7cb6b31..a2d88cf 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -70,8 +70,8 @@ void Decl::updateOutOfDate(IdentifierInfo &II) const {
 #define ABSTRACT_DECL(DECL)
 #include "clang/AST/DeclNodes.inc"
 
-void *Decl::operator new(std::size_t Size, const ASTContext &Context,
-                         Decl::DeclID ID, std::size_t Extra) {
+void *Decl::operator new(std::size_t Size, const ASTContext &Context, DeclID ID,
+                         std::size_t Extra) {
   // Allocate an extra 8 bytes worth of storage, which ensures that the
   // resulting pointer will still be 8-byte aligned.
   static_assert(sizeof(unsigned) * 2 >= alignof(Decl),