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

tests/inputs/test_align_tts.json

@@ -148,7 +148,7 @@
     "datasets":   // List of datasets. They all merged and they get different speaker_ids.
     [
         {
-            "name": "ljspeech",
+            "formatter": "ljspeech",
             "path": "tests/data/ljspeech/",
             "meta_file_train": "metadata.csv",
             "meta_file_val": "metadata.csv",