Move diagnostic/printer.h into the public API

Bug: None
Change-Id: I6dc33f3e589de80b225199fb01a0d80df774ada3
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/31740
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Commit-Queue: dan sinclair <dsinclair@chromium.org>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>
diff --git a/include/tint/tint.h b/include/tint/tint.h
index dbbffac..ade7f9c 100644
--- a/include/tint/tint.h
+++ b/include/tint/tint.h
@@ -20,6 +20,7 @@
 
 #include "src/ast/pipeline_stage.h"
 #include "src/context.h"
+#include "src/diagnostic/printer.h"
 #include "src/inspector/inspector.h"
 #include "src/reader/reader.h"
 #include "src/transform/bound_array_accessors_transform.h"
diff --git a/samples/main.cc b/samples/main.cc
index 5494ef1..53d490a 100644
--- a/samples/main.cc
+++ b/samples/main.cc
@@ -24,7 +24,6 @@
 #include "spirv-tools/libspirv.hpp"
 #endif  // TINT_BUILD_SPV_READER
 
-#include "src/diagnostic/printer.h"
 #include "tint/tint.h"
 
 namespace {