Allow entity name translations

Allow not setting names to sensors to leverage translated default names in Home Assistant

So you can define a ESPHome device and for example a Temperature sensor, without setting a name explicitly and that will still turn up as a sensor in HA, with a translated name.

**Challenges:**

- expose to ha boolean set by default (internal flag to false) ?
- import translations into ESPHome for webserver
- name None will use device name, how to handle that ?

**Implement the same logic as HA:**

- use name field to explicitly set a name ?
- use translation key to set a translatable name ?
- use device type

**Idea:**

- If the user has not specified `id` or `name`, can we assume they want to expose it to HA with automatic translation keys?