添加 Azure TTS 作为内置 TTS (#28)

* feat(plugins/tts): add azure tts

* fix(tts/azure): fix 400 error

Replacing special symbol.

* fix(tts/azure): fix error msg

* fix(tts/azure): ignore zero-length arraybuffer

* feat(tts/azure): select first voice as default value

* fix(tts/azure): escape special characters for xml payload

* fix(tts/azure): check voice list before generate ssml

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Co-authored-by: moomewa <1345514736@qq.com>