fix(gql): define ANTLR4CPP_STATIC for Windows builds

[adsharma]

Problem

The GQL extension links antlr4_runtime, which is built as a static library (see third_party/antlr4_runtime/CMakeLists.txt). On Windows its headers default to __declspec(dllimport) unless ANTLR4CPP_STATIC is defined.

The GQL object libraries compile their sources without that define, so MSVC emits references to a non-existent ANTLR DLL for inline/compiler-generated members. This surfaces as:

gql_function.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual bool __cdecl antlr4::tree::AbstractParseTreeVisitor::shouldVisitNextChild(class antlr4::tree::ParseTree *,class std::any const &)"
gql_function.cpp.obj : error LNK2001: unresolved external symbol "public: virtual __cdecl antlr4::tree::AbstractParseTreeVisitor::~AbstractParseTreeVisitor(void)"

Fix

Define ANTLR4CPP_STATIC for the gql extension, so those members are emitted locally in the extension's own TUs. This matches how the core library builds its own ANTLR consumers (src/CMakeLists.txt).

Linux/macOS builds are unaffected — ANTLR4CPP_STATIC is only consulted in the MSVC branch of antlr4-common.h.