Implement experiment details page

[zackcl]

Resolves #2560

The PR includes implementing all the section card components on the experiment details page. The section card's child components (e.g., table) will be implemented in a separate PR. The modals opened by these section cards (e.g., Add Condition modal) will also be implemented in a separate PR. I will create tickets for implementing these.

FYI, I had to update the backend in order to create an experiment with empty decision points and conditions. Please review if the changes look correct.

[bcb37]

A couple questions:

1. Do we want to create experiments initially with 'DRAFT' status?
2. Do we have a plan to support factorial experiments? - currently it errors when you try to create a factorial experiment because the backend expects factors to be supplied; and it looks like the UI for factorial experiments isn't implemented yet.

[zackcl]

2. The UI for factorial experiments isn’t there yet — I’ve always thought of it as part of the v2 design refresh. I can work on creating the designs in Figma, but we should probably check with April about that.

@zackcl Ok, if that's the case we should remove 'Experiment Type' selector for v1, since choosing factorial will be broken until v2.

[bcb37]

2. The UI for factorial experiments isn’t there yet — I’ve always thought of it as part of the v2 design refresh. I can work on creating the designs in Figma, but we should probably check with April about that.

@zackcl Ok, if that's the case we should remove 'Experiment Type' selector for v1, since choosing factorial will be broken until v2.

@zackcl sorry I accidentally edited your comment. Creating an issue to initialize experiments with 'DRAFT' status makes sense to me.

[zackcl]

@bcb37 I've disabled the Factorial Experiment Type option from the modal, and also created an issue for "DRAFT" status: #2586

[bcb37]

Since we're removing support for factorial experiments in the new frontend, we'll probably have to do something similar to what we did with 'old-style' segments and switch to the legacy editor when an attempt is made to edit a factorial experiment that already exists (or is imported). We'll need a ticket to add the logic to edit factorial experiments in the stepper.

[zackcl]

I've reverted the commits I made for supporting factorial experiments on the legacy details page. Feel free to review and approve the PR.

[danoswaltCL]

The majority of this is all good to go, looks great, just a couple of minor questions. One of the questions is on Experiment types and that can be punted to another story. I think we can make our lives easier with stronger Experiment types that keep better aligned with the backend. These are the most complex and most important objects we deal with and often have little bugs where properties are undefined, etc... if there's any tech-debt that we tackle in parallel with this redesign I think this would be a good spot, would speed things up later.