Add the following metrics for elixir_cache:

Metrics included:

• elixir_cache.cache.get.count
• elixir_cache.cache.get.miss.count
• elixir_cache.cache.get.error.count
• elixir_cache.cache.put.count
• elixir_cache.cache.delete.count
• elixir_cache.cache.get.duration.millisecond