Improve pipeline stage creation process

### Epic

_No response_

### Description

**As a pipeline user**

**I want to have a more intuitive interface for creating pipeline stages**

**So that I can more easily create the pipeline stages I want to create**

As noted from @cstns , feedback has been received that the interface for creating a pipeline stage is not very intuitive.

Here is the current interface:

At present, it is not clear what is the starting point of the stage, nor what is the target of the stage, nor what will happen when one of the snapshot actions is chosen.

Improve this UI. A step-by-step process would be more helpful. The user should be guided to:
- Name the stage
- Determine what is the data to be sent forward in the pipeline (an instance, a snapshot, a subflow)
- Determine where the data will be sent to

### Which customers would this be available to

None

### Acceptance Criteria

- [ ] criteria 1
- [ ] criteria 2
- [ ] criteria 3
- ...

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate