[Challenge] Allow to change challenge type (if challenge has no completions]

Primarily, I am most keen on retaining the following when I change a challenge type from e.g. Photo Challenge to Standard Challenge in descending order of priority:

1. Image

2. Title

3. Description

4. Feedback Message

5. Unlocking Rule/Achievement Rule

Some Considerations:

a. The challenge must not have been completed before, else what it does is it duplicates the challenge, and allow the user to change the type after. (there is room for some nice UX touch).

b. It can also be the default question whenever a challenge is being copied, and the admin will be prompted on whether they are keeping the same challenge type.

The rest are not too important. I strongly would like to push for this as personally this has created a lot of friction for myself. If Gametize pride itself as being a very test-driven tool, the iteration and change process has to be very easy.