Katacoda feature test: Refresh files every step

[christiemolloy]

For modules where we have steps that aren't progressive i.e. each step is its own task that is separate from the next step.... it would be great to be able to "wipe" the text inside the files that are open as soon as the user clicks the button to go to the next step.

Users are expecting steps to build off each other when the code from the previous step is still in the editor.

An example is this: https://www.katacoda.com/patternfly/courses/html-css/module-2

[christiemolloy]

@dgutride reported that we can clear the file for each step, however Katacoda isn't recognizing this change so it doesn't refresh contents in the iframe --> captured here #186