So in my experience there isn't a single job with a defined remit that does this, instead a range of positions do bits of this

Business Analysist, solution architects, presales engineers, product owners, sometimes even project delivery managers and developer team leads have to deal with this.

You might stand better luck of getting into one of these positions in a consultancy company, because there each customer has a separate set of requirements and often they don't have enough of these people.