EngineManifestモデルの追加機能群をOptionalにする

[y-chan]

内容

題の通りです。EngineManifestの破壊的変更を緩和します。

関連 Issue

• ref APIサーバとして立てるとvoicevoxが立ち上がらない #693
• vvlib_manifest.jsonをバリデートするようにする #694 (comment)

[github-actions]

Coverage Result

Resultを開く

Name	Stmts	Miss	Cover
voicevox_engine/init.py	2	1
voicevox_engine/acoustic_feature_extractor.py	75	0
voicevox_engine/dev/synthesis_engine/init.py	3	1
voicevox_engine/dev/synthesis_engine/mock.py	36	2
voicevox_engine/downloadable_library.py	93	5
voicevox_engine/full_context_label.py	162	3
voicevox_engine/kana_parser.py	86	1
voicevox_engine/metas/Metas.py	33	0
voicevox_engine/metas/MetasStore.py	29	14
voicevox_engine/metas/init.py	2	0
voicevox_engine/model.py	160	9
voicevox_engine/mora_list.py	5	0
voicevox_engine/part_of_speech_data.py	5	0
voicevox_engine/preset/Preset.py	12	0
voicevox_engine/preset/PresetError.py	3	1
voicevox_engine/preset/PresetManager.py	81	2
voicevox_engine/preset/init.py	4	0
voicevox_engine/setting/Setting.py	11	0
voicevox_engine/setting/SettingLoader.py	19	0
voicevox_engine/setting/init.py	3	0
voicevox_engine/synthesis_engine/init.py	5	0
voicevox_engine/synthesis_engine/core_wrapper.py	201	159
voicevox_engine/synthesis_engine/make_synthesis_engines.py	57	49
voicevox_engine/synthesis_engine/synthesis_engine.py	130	11
voicevox_engine/synthesis_engine/synthesis_engine_base.py	67	9
voicevox_engine/user_dict.py	144	11
voicevox_engine/utility/init.py	5	0
voicevox_engine/utility/connect_base64_waves.py	37	0
voicevox_engine/utility/core_version_utility.py	9	2
voicevox_engine/utility/mutex_utility.py	11	1
voicevox_engine/utility/path_utility.py	26	8
TOTAL	1516	289

[Hiroshiba]

LGTM！！