test(cdclient): benchmark startup and a big inventory with and without the fdb

Skipped unless DLU_FDB_BENCH_XML names a character save; prints startup
time, inventory load time and resident memory (private and file-backed,
on Linux) for DLU_FDB_BENCH_MODE=fdb or sqlite.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/dGameTests/CMakeLists.txt

@@ -28,6 +28,7 @@ set(DGAMETEST_SOURCES
 	"SpiderQueenTests.cpp"
 	"TacArcTests.cpp"
 	"CDFdbTests.cpp"
+	"CDFdbBenchmark.cpp"
 )
 
 add_subdirectory(dComponentsTests)