Make validation error formatting more consistent

- Updates error message formatting to ensure they end with a newline to
   prevent errors from running together.
 - Updated all encoder/device context messages to normalize their format
   and include more information.
 - Update Abseil formatter to make objects indicate if they are an error
   object in the formatted string. (ie: [Invalid BindGroup])
 - Added fallback code in case a context message doesn't format
   correctly to aid in debugging.

Bug: dawn:1154
Change-Id: Id27b11305cf8efcca343597f90489dde5552c775
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/68200
Commit-Queue: Brandon Jones <bajones@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>

generator/templates/dawn_native/webgpu_absl_format.cpp

@@ -94,6 +94,9 @@ namespace dawn_native {
             return {true};
         }
         s->Append("[");
+        if (value->IsError()) {
+            s->Append("Invalid ");
+        }
         s->Append(ObjectTypeAsString(value->GetType()));
         const std::string& label = value->GetLabel();
         if (!label.empty()) {
@@ -112,6 +115,9 @@ namespace dawn_native {
             return {true};
         }
         s->Append("[");
+        if (value->IsError()) {
+            s->Append("Invalid ");
+        }
         s->Append(ObjectTypeAsString(value->GetType()));
         const std::string& label = value->GetLabel();
         if (!label.empty()) {