Extract common parts of snippet and blob pages into partial

app/views/projects/blob/_header.html.haml

 - blame = local_assigns.fetch(:blame, false)
 .js-file-title.file-title-flex-parent
-  .file-header-content
-    = blob_icon blob.mode, blob.name
-
-    %strong.file-title-name
-      = blob.name
-
-    = copy_file_path_button(blob.path)
-
-    %small
-      = number_to_human_size(blob.raw_size)
+  = render 'projects/blob/header_content', blob: blob
 
   .file-actions.hidden-xs
     = render 'projects/blob/viewer_switcher', blob: blob unless blame

app/views/projects/blob/_header_content.html.haml

+.file-header-content
+  = blob_icon blob.mode, blob.name
+
+  %strong.file-title-name
+    = blob.name
+
+  = copy_file_path_button(blob.path)
+
+  %small
+    = number_to_human_size(blob.raw_size)

app/views/shared/snippets/_blob.html.haml

 - blob = @snippet.blob
 .js-file-title.file-title-flex-parent
-  .file-header-content
-    = blob_icon blob.mode, blob.path
-
-    %strong.file-title-name
-      = blob.path
-
-    = copy_file_path_button(blob.path)
-
-    %small
-      = number_to_human_size(blob.raw_size)
+  = render 'projects/blob/header_content', blob: blob
 
   .file-actions.hidden-xs
     = render 'projects/blob/viewer_switcher', blob: blob