Editor REST Client: Easily manage long list of POST parameters

Consider a POST request with many POST parameters:

POST /submit.php HTTP 1.1
Content-Type: application/x-www-form-urlencoded

foo1=bar&foo2=bar&foo3=bar&foo4=bar&foo5=bar&foo6=bar&foo7=bar&foo8=bar&foo9=bar

I would like to organize the parameters one per line, and have PhpStorm do some auto-formatting on them to properly concatenate and urlencode them. Is this possible? This is how I imagine it looking:

POST /submit.php HTTP 1.1
Content-Type: application/x-www-form-urlencoded

foo1=bar
foo2=bar
foo3=bar
foo4=bar
foo5=bar
foo6=bar
foo7=bar
foo8=bar
foo9=bar

As an IdeadVIM user I could do the concatenation with a VIM macro, but I wonder that PhpStorm may have some functionality built-in. I did try indenting the lines, that did not help. Note that Postman and other REST clients do have this feature.