Added title attribute to enties in tree view

Closes #18353

app/views/projects/tree/_blob_item.html.haml

 %tr{ class: "tree-item #{tree_hex_class(blob_item)}" }
   %td.tree-item-file-name
     = tree_icon(type, blob_item.mode, blob_item.name)
-    %span.str-truncated
-      = link_to blob_item.name, namespace_project_blob_path(@project.namespace, @project, tree_join(@id || @commit.id, blob_item.name))
+    - file_name = blob_item.name
+    = link_to namespace_project_blob_path(@project.namespace, @project, tree_join(@id || @commit.id, blob_item.name)), title: file_name do
+      %span.str-truncated= file_name
   %td.tree_time_ago.cgray
     = render 'projects/tree/spinner'
   %td.hidden-xs.tree_commit

app/views/projects/tree/_tree_item.html.haml

 %tr{ class: "tree-item #{tree_hex_class(tree_item)}" }
   %td.tree-item-file-name
     = tree_icon(type, tree_item.mode, tree_item.name)
-    %span.str-truncated
     - path = flatten_tree(tree_item)
-      = link_to path, namespace_project_tree_path(@project.namespace, @project, tree_join(@id || @commit.id, path))
+    = link_to namespace_project_tree_path(@project.namespace, @project, tree_join(@id || @commit.id, path)), title: path do
+      %span.str-truncated= path
   %td.tree_time_ago.cgray
     = render 'projects/tree/spinner'
   %td.hidden-xs.tree_commit