Fix AI types

[reynaldichernando]

• remove constructor
• remove global methods, setAuthToken, setAPIOrigin
• use stricter type (removing [key: string]: unknown;)
• fix streaming intellisense
• add missing imageURLArray handling
• fix all positional testmode and options
• simplify txt2speech
• add missing options everywhere
• add missing return type for chat
• fix return type speech2speech

and probably some more that i didn't write here

[reynaldichernando]

after some more thinking, even if we miss a type or two, it won't be a breaking change for end user, because they can still disable the typescript check for a particular type