Editable mechanics nodes

[zkat]

You should be able to edit mechanics nodes without having to drop into full kdl edit mode

Probably the best way to do this is to have a small edit button either on individual nodes or on the entire mechanics block that turns things into individual forms that can be edited, using the argument names.

This is kind of a project but I think it's not great to expect folks to manually edit kdl unless they're technical folks

[zkat]

A big chunk of this has been taken care of now that #407 has landed and all the work involved to get that working.

This is still a fairly large task because we have to create edit forms for every node type (or figure out some system to do it generically).