d-vector handling (#1945)

* Update BaseDatasetConfig

- Add dataset_name
- Chane name to formatter_name

* Update compute_embedding

- Allow entering dataset by args
- Use released model by default
- Use the new key format

* Update loading

* Update recipes

* Update other dep code

* Update tests

* Fixup

* Load multiple embedding files

* Fix argument names in dep code

* Update docs

* Fix argument name

* Fix linter

docs/source/tutorial_for_nervous_beginners.md

@@ -84,7 +84,7 @@ We still support running training from CLI like in the old days. The same traini
         "print_eval": true,
         "mixed_precision": false,
         "output_path": "recipes/ljspeech/glow_tts/",
-        "datasets":[{"name": "ljspeech", "meta_file_train":"metadata.csv", "path": "recipes/ljspeech/LJSpeech-1.1/"}]
+        "datasets":[{"formatter": "ljspeech", "meta_file_train":"metadata.csv", "path": "recipes/ljspeech/LJSpeech-1.1/"}]
     }
     ```
 
@@ -120,6 +120,3 @@ $ tts-server -h # see the help
 $ tts-server --list_models  # list the available models.
 ```
 ![server.gif](https://github.com/coqui-ai/TTS/raw/main/images/demo_server.gif)
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-
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