[lldb] Move clang-based files out of Symbol

Summary:
This change represents the move of ClangASTImporter, ClangASTMetadata,
ClangExternalASTSourceCallbacks, ClangUtil, CxxModuleHandler, and
TypeSystemClang from lldbSource to lldbPluginExpressionParserClang.h

This explicitly removes knowledge of clang internals from lldbSymbol,
moving towards a more generic core implementation of lldb.

Reviewers: JDevlieghere, davide, aprantl, teemperor, clayborg, labath, jingham, shafik

Subscribers: emaste, mgorny, arphaman, jfb, usaxena95, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D73661
diff --git a/lldb/source/API/SystemInitializerFull.cpp b/lldb/source/API/SystemInitializerFull.cpp
index 9d566b5..d518c57 100644
--- a/lldb/source/API/SystemInitializerFull.cpp
+++ b/lldb/source/API/SystemInitializerFull.cpp
@@ -22,7 +22,6 @@
 #include "lldb/Host/Host.h"
 #include "lldb/Initialization/SystemInitializerCommon.h"
 #include "lldb/Interpreter/CommandInterpreter.h"
-#include "lldb/Symbol/TypeSystemClang.h"
 #include "lldb/Utility/Timer.h"
 
 #include "Plugins/ABI/MacOSX-arm/ABIMacOSX_arm.h"
@@ -96,6 +95,7 @@
 #include "Plugins/SymbolVendor/ELF/SymbolVendorELF.h"
 #include "Plugins/SymbolVendor/wasm/SymbolVendorWasm.h"
 #include "Plugins/SystemRuntime/MacOSX/SystemRuntimeMacOSX.h"
+#include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
 #include "Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.h"
 #include "Plugins/UnwindAssembly/x86/UnwindAssembly-x86.h"