Adding support for playback to L32/S32/F16 canvas.

Playback of my test GM works correctly on both raster and GPU, in all three modes.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1893393002

Review URL: https://codereview.chromium.org/1893393002
diff --git a/tools/skiaserve/skiaserve.cpp b/tools/skiaserve/skiaserve.cpp
index fd96251..e71be0f 100644
--- a/tools/skiaserve/skiaserve.cpp
+++ b/tools/skiaserve/skiaserve.cpp
@@ -39,6 +39,7 @@
         fHandlers.push_back(new BreakHandler);
         fHandlers.push_back(new BatchesHandler);
         fHandlers.push_back(new BatchBoundsHandler);
+        fHandlers.push_back(new ColorModeHandler);
     }
 
     ~UrlManager() {