Stack: Promoting stack from experiments package to OUFR package.

[khmakoto]

Pull request checklist

• Addresses an existing issue: Fixes New Component: Stack #5419
• Include a change request file using $ npm run change

Description of changes

This PR has the purpose of promoting the Stack component from the experiments package to the office-ui-fabric-react package.

As part of this process, it was decided that we should change the approach we were using in the experiments package of having two separate components, HorizontalStack and VerticalStack, and instead have a single component Stack with a boolean property horizontal that determines if the stack is horizontal or vertical, with a vertical stack being the default.

This change required modifying existing examples, tests and usage of Stack inside other components throughout the experiments package. The HorizontalStack and VerticalStack pages in the experiments website have also been removed and a Stack page has been added to the office-ui-fabric-react website as part of this change.

Focus areas to test

All the existing tests (snapshots, vr-tests, etc) for HorizontalStack and VerticalStack have been modified to use the singular Stack component and the new component has been tested against all of them to ensure conformance with how the previous components worked.

TO-DOs

• Add the wrap functionality to vertical Stacks.
  • Add examples in documentation page.
  • Add snapshot tests.
  • Add vr-tests.
• Finish documentation on Stack component.
  • Add overview.
  • Add Do's.
  • Add Dont's.

Microsoft Reviewers: Open in CodeFlow

[khmakoto]

@micahgodbolt I mentioned this in the email thread, but just to have it here, I updated the code so that the left/right/center notation is now start/end/center to adhere to LTR.

[kenotron]

@khmakoto - I think it's a good time for you to write up a short description of high levels that you had to do to upgrade. I also think @micahgodbolt had a check list of stuff we really need to follow with promotions now that we've got the API nailed down.

Here's an example #7254

[micahgodbolt]

We also have an issue for stack that it would be great to update/link to #5419

[micahgodbolt]

@khmakoto i've updated the original issue with or current 'new component' template. Can you move your comments, todos, code examples etc into that issue.

Another thought is that we should focus on getting Stack correct in Experiments before moving it over to OUFR. i.e. smaller, more focused PRs to prep this control. Then one big PR to simply move it.

[dzearing]

Closing, please resolve and reopen when ready.