Speaker Request for external option remote speaker

**Describe the problem you have/What new integration you would like**

id like to see option for remote speaker option under the
```
speaker:
```
not just is2
this way i can have a microphone on the the desk... and i could output to multiple speakers as as
```
group.whatever
```
or a single speaker sitting on the ceiling so it could be louder... and this way you can have multiple microphones in a single room and they all out to 1 Single big speaker on the ceiling..

so you could have 5 microhpones in 1 room and they all link to 1 speaker on the ceiling not to the specific esp device
**Please describe your use case for this integration and alternatives you've tried:**

id like to see under the
```
speaker:
```
option to use a remote speaker like a another wifi speaker so when using the voice assistant you dont need a speaker on the the device.. just a mic... and you can output to like
```
voice_assistant:
microphone: mic
use_wake_word: true
noise_suppression_level: 2
auto_gain: 31dBFS
volume_multiplier: 2.0
speaker: big_speaker
id: assist
sensor:
- platform: homeassistant
id: big_speaker
entity_id: media_player.speaker_3_esphome_i2s_media_player
```
or
```
sensor:
- platform: homeassistant
id: big_speaker
entity_id: group.group_of speakers

or

sensor:
- platform: homeassistant
id: big_speaker
entity_id: - media_player.speaker_3_esphome_i2s_media_player
- media_player.speaker_2_esphome_i2s_media_player
- media_player.speaker_1_esphome_i2s_media_player

````

**Additional context**

Start with the voice_assistant and speaker configuration examples in the issue, then trace how speaker outputs are currently represented. The issue names no files or tests; done would require a defined, supported configuration path for routing voice-assistant audio to a remote or grouped speaker.

Written by the indexing model from the issue text.