Give pipeline variables as query string parameters from /pipelines/new page

Problem to solve

I would like to be able to give pipeline variables as parameters of the /pipelines/new request.

Further details

To create a new pipeline, I usually go to <repo>/pipelines/new

I already can add a ref parameter to automatically choose the branch name or tag as <repo>/pipelines/new?ref=master

I would like to add a way to populate variables in a similar way than the ref parameter.

Proposal

We will add support for query strings as follows: repo/pipelines/new?ref=master&var[key1]=value1&file_var[key2]=value2

What does success look like, and how can we measure that?

Ideally, the previous url would prints out :

Links / references