feat(Text2Speech): Add support for text to speech

[lukasdotcom]

This creates an implementation for text to speech. (nextcloud/server#52051)

I don't really know for sure what to do about the voices because I couldn't find an endpoint that lists the voices. Right now its just hardcoded to one of openai's voices. Some ideas that I have are:

1. Make the input field text for the voice and just fail when an invalid voice is given
2. Detect when open ai endpoint is being used and then use hardcoded list
3. Let admin create a list of valid values to use

Openai's documentation for text to speech: https://platform.openai.com/docs/guides/text-to-speech#voice-options

[julien-nc]

Nicely done!
Can you use tabs for indentation in Php files?
You can fix all your files at once with composer run cs:fix

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[kyteinsky]

thanks for the nice work!
It works wonderfully.

btw, the limit for the input is 4096 characters (https://platform.openai.com/docs/api-reference/audio/createSpeech#audio-createspeech-input). It would be a QoL improvement to split the sentences as such but it can be a feature for later.

[lukasdotcom]

Also I rebased this branch to make sure that the change I had to add for every test also was added to the emoji provider.

$iResponse->method('getHeader')->with('Content-Type')->willReturn('application/json');

[kyteinsky]

some minor changes

[kyteinsky]

thanks a lot 🚀

[lukasdotcom]

Note: Will need to fix the failing unit tests.