Watch heex and sface templates (#583)

* Watch heex and sface templates

* Run formatter

Author: msaraiva

apps/language_server/lib/language_server/server.ex

@@ -71,7 +71,18 @@ defmodule ElixirLS.LanguageServer.Server do
     end
   end
 
-  @watched_extensions [".ex", ".exs", ".erl", ".hrl", ".yrl", ".xrl", ".eex", ".leex"]
+  @watched_extensions [
+    ".ex",
+    ".exs",
+    ".erl",
+    ".hrl",
+    ".yrl",
+    ".xrl",
+    ".eex",
+    ".leex",
+    ".heex",
+    ".sface"
+  ]
 
   ## Client API