Implement texture_depth_multisampled_2d

Implemented for all readers and writers.

Cleaned up some verbose code in sem::Function and the Inspector in the
process.

Fixed: tint:1032
Change-Id: Ia6f2f59e6d2e511c89160b97be990e8b7c9828d9
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/59664
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>
Reviewed-by: James Price <jrprice@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Auto-Submit: Ben Clayton <bclayton@google.com>

samples/main.cc

@@ -351,6 +351,9 @@ std::string ResourceTypeToString(
       return "WriteOnlyStorageTexture";
     case tint::inspector::ResourceBinding::ResourceType::kDepthTexture:
       return "DepthTexture";
+    case tint::inspector::ResourceBinding::ResourceType::
+        kDepthMultisampledTexture:
+      return "DepthMultisampledTexture";
     case tint::inspector::ResourceBinding::ResourceType::kExternalTexture:
       return "ExternalTexture";
   }