fix(elm): Room form

[mrapacz]

Type

Bug

Current behaviour

• it is possible to insert a room that doesn't contain any category
• there is also no placeholder for when there are no categories chosen
• all the other forms have labels above the actual inputs, there is none above room description
• while using other forms where you have to pick something from a list, hitting enter equals choosing an item. Currently hitting enter while choosing the categories in room form submits the form.

Expected behaviour
The above should not be happening

Motivation / use case
UX and safety

[pmrukot]

Also, the form is not being cleared after submitting ☝️

[mrapacz]

I'm removing it from the deployment milestone because we are not going to have the forms displayed in the first version. It should be fixed/removed anyway.