feat(bing): enable the image generation function(BIC) for cli mode (#401)

[danny-avila]

@timefox if you would like to look this over, I'm looking to keep this repo updated with features like this

1. Enable the image generation function(BIC) for cli mode. Now it can return a list of image urls in plain text or markdown syntax format. And it also works in server mode with an option.
2. The 'returnData' of BingAIClient's sendMessage will contain a 'bic' object if bic is used in this message. This object is under 'details'. It contains prompt used and the type of bic result. Further more, if a url list is retruned, it can be obtained through an array object called 'images'.
3. This the image generation function can now be switched on and off separately in both server and cli modes. And you can use 3 different types of generation, see settings.example.js for details.
4. Since the 'creative' tone style is required for BIC, add an option to set the default tone style in settings.js.
5. For server mode, fix the 'genImage' option which is set by client side(It can't be turn off once turn on at before).
6. bump @timefox/bic-sydney.

[danny-avila]

resolving conflicts