[lldb] Abstract scoped timer logic behind LLDB_SCOPED_TIMER (NFC)

This patch introduces a LLDB_SCOPED_TIMER macro to hide the needlessly
repetitive creation of scoped timers in LLDB. It's similar to the
LLDB_LOG(F) macro.

Differential revision: https://reviews.llvm.org/D93663

lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

@@ -576,9 +576,7 @@ size_t ObjectFileELF::GetModuleSpecifications(
             uint32_t core_notes_crc = 0;
 
             if (!gnu_debuglink_crc) {
-              static Timer::Category func_cat(LLVM_PRETTY_FUNCTION);
-              lldb_private::Timer scoped_timer(
-                  func_cat,
+              LLDB_SCOPED_TIMERF(
                   "Calculating module crc32 %s with size %" PRIu64 " KiB",
                   file.GetLastPathComponent().AsCString(),
                   (length - file_offset) / 1024);