janus.d.ts: fix typo and update PluginCreateAnswerParam to use tracks

[veeting]

Hello!

This is a very simple PR affecting only the janus.d.ts file.

1/ We found a typo where TrackOptions should be TrackOption 2/ We also have updated the PluginCreateAnswerParam type to have the newer tracks parameter and marked the media as deprecated. (same as OfferParam)

Best regards, Aymeric

[lminiero]

This looks good to me but I'm not very experienced with TypeScript, so I'll let @atoppi have the final word!

[atoppi]

lgtm :+1:

[lminiero]

Ack, merging then!