Adds strformat code-gen for helping auto-generate readable strings for structs.

- Adds generator infra for absl::StrFormat for bind group structs and types.
- Uses absl::ParsedFormat to avoid multiple parsing for format strings.

Bug: dawn:549
Change-Id: Ida4ca65eb85c4474c492161c8ae34f53bd692a3c
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/81944
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Loko Kung <lokokung@google.com>

generator/dawn_json_generator.py

@@ -684,6 +684,15 @@ def as_wireType(metadata, typ):
         return as_cppType(typ.name)
 
 
+def as_formatType(typ):
+    # Unsigned integral types
+    if typ.json_data['type'] in ['bool', 'uint32_t', 'uint64_t']:
+        return 'u'
+
+    # Defaults everything else to strings.
+    return 's'
+
+
 def c_methods(params, typ):
     return typ.methods + [
         x for x in [
@@ -753,7 +762,8 @@ def make_base_render_params(metadata):
             'as_jsEnumValue': as_jsEnumValue,
             'convert_cType_to_cppType': convert_cType_to_cppType,
             'as_varName': as_varName,
-            'decorate': decorate
+            'decorate': decorate,
+            'as_formatType': as_formatType
         }