[LLD][COFF] Add support for --time-trace (#68236)

This adds support for generating Chrome-tracing .json profile traces in
the LLD COFF driver.

Also add the necessary time scopes, so that the profile trace shows in
great detail which tasks are executed.

As an example, this is what we see when linking a Unreal Engine
executable:

![image](https://github.com/llvm/llvm-project/assets/37383324/b2e26eb4-9d37-4cf9-b002-48b604e7dcb7)

lld/COFF/Config.h

@@ -286,6 +286,7 @@ struct Configuration {
   uint32_t minorSubsystemVersion = 0;
   uint32_t timestamp = 0;
   uint32_t functionPadMin = 0;
+  uint32_t timeTraceGranularity = 0;
   bool dynamicBase = true;
   bool allowBind = true;
   bool cetCompat = false;
@@ -309,6 +310,7 @@ struct Configuration {
   bool swaprunNet = false;
   bool thinLTOEmitImportsFiles;
   bool thinLTOIndexOnly;
+  bool timeTraceEnabled = false;
   bool autoImport = false;
   bool pseudoRelocs = false;
   bool stdcallFixup = false;

lld/COFF/DebugTypes.cpp

@@ -29,6 +29,7 @@
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/Parallel.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/TimeProfiler.h"
 
 using namespace llvm;
 using namespace llvm::codeview;
@@ -1068,13 +1069,15 @@ TypeMerger::~TypeMerger() = default;
 void TypeMerger::mergeTypesWithGHash() {
   // Load ghashes. Do type servers and PCH objects first.
   {
+    llvm::TimeTraceScope timeScope("Load GHASHes");
     ScopedTimer t1(ctx.loadGHashTimer);
     parallelForEach(dependencySources,
                     [&](TpiSource *source) { source->loadGHashes(); });
     parallelForEach(objectSources,
                     [&](TpiSource *source) { source->loadGHashes(); });
   }
 
+  llvm::TimeTraceScope timeScope("Merge types (GHASH)");
   ScopedTimer t2(ctx.mergeGHashTimer);
   GHashState ghashState;