Add diag::Formatter::Style::print_newline_at_end

Automatically prints a newline at the end of the last diagnostic in a list. Defaults to true.

Disabled for many tests that assume no newline at end of string.

Change-Id: Id1c2f7771f03f22d926fafc2bebebcef056ac5e8
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/37260
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>
diff --git a/src/reader/wgsl/parser_impl.h b/src/reader/wgsl/parser_impl.h
index c523d06..9a4e478 100644
--- a/src/reader/wgsl/parser_impl.h
+++ b/src/reader/wgsl/parser_impl.h
@@ -297,7 +297,7 @@
 
   /// @returns the parser error string
   std::string error() const {
-    diag::Formatter formatter{{false, false, false}};
+    diag::Formatter formatter{{false, false, false, false}};
     return formatter.format(diags_);
   }