[directwrite] Add hb_directwrite_face_create_from_file_or_fail()

Just loads the blob from file and creates a face from it.

New API:
+hb_directwrite_face_create_from_file_or_fail()

docs/harfbuzz-sections.txt

@@ -361,6 +361,7 @@ hb_coretext_font_set_funcs
 <SECTION>
 <FILE>hb-directwrite</FILE>
 hb_directwrite_face_create
+hb_directwrite_face_create_from_file_or_fail
 hb_directwrite_face_create_from_blob_or_fail
 hb_directwrite_face_get_dw_font_face
 hb_directwrite_font_create

src/hb-directwrite.cc

@@ -1026,6 +1026,33 @@ hb_directwrite_face_create (IDWriteFontFace *dw_face)
 				    _hb_directwrite_face_release);
 }
 
+/**
+ * hb_directwrite_face_create_from_file_or_fail:
+ * @file_name: A font filename
+ * @index: The index of the face within the file
+ *
+ * Creates an #hb_face_t face object from the specified
+ * font file and face index.
+ *
+ * This is similar in functionality to hb_face_create_from_file_or_fail(),
+ * but uses the DirectWrite library for loading the font file.
+ *
+ * Return value: (transfer full): The new face object, or `NULL` if
+ * no face is found at the specified index or the file cannot be read.
+ *
+ * XSince: REPLACEME
+ */
+hb_face_t *
+hb_directwrite_face_create_from_file_or_fail (const char   *file_name,
+					      unsigned int  index)
+{
+  auto *blob = hb_blob_create_from_file_or_fail (file_name);
+  if (unlikely (!blob))
+    return nullptr;
+
+  return hb_directwrite_face_create_from_blob_or_fail (blob, index);
+}
+
 /**
  * hb_directwrite_face_create_from_blob_or_fail:
  * @blob: A blob containing the font data

src/hb-directwrite.h

@@ -34,6 +34,10 @@ HB_BEGIN_DECLS
 HB_EXTERN hb_face_t *
 hb_directwrite_face_create (IDWriteFontFace *dw_face);
 
+HB_EXTERN hb_face_t *
+hb_directwrite_face_create_from_file_or_fail (const char   *file_name,
+					      unsigned int  index);
+
 HB_EXTERN hb_face_t *
 hb_directwrite_face_create_from_blob_or_fail (hb_blob_t    *blob,
 					      unsigned int  index);

src/hb-face.cc

@@ -357,7 +357,7 @@ static struct supported_face_loaders_t {
 #endif
 #ifdef HAVE_DIRECTWRITE
   {"directwrite",
-   nullptr, //hb_directwrite_face_create_from_file_or_fail,
+   hb_directwrite_face_create_from_file_or_fail,
    hb_directwrite_face_create_from_blob_or_fail
   },
 #endif