Support for inline LiveView templates

What is the right place to add support for inline templates?

Here is an example:

```elixir
defmodule AppWeb.ThermostatLive do
use Phoenix.LiveView

def render(assigns) do
~L"""

def mount(_params, %{"current_user_id" => user_id}, socket) do
temperature = Thermostat.get_user_reading(user_id)
{:ok, assign(socket, :temperature, temperature)}
end
end
```

Ideally I would like the part inside the sigil to be highlighted as eex html template.