[Bug] Fix dark mode on storybook web Docs pages

[narin]

Ticket #53

Description of Change

Quick fix to enable dark mode toggling on Docs pages. Dark mode was previously only working on the stories. This seems to be a known bug for Storybook. Found a workaround here. This also required renaming preview.ts to preview.tsx since it now includes React code.

Testing Packages

N/A (tested locally)

Screenshots/Video

Screen.Recording.2024-02-21.at.3.13.31.PM.mov

Testing

• Tested on iOS
• Tested on Android
• Tested on Web

PR Checklist

Code reviewer validation:

• General
  • PR is linked to ticket(s)
  • PR has changelog label applied if it's to be included in the changelog
  • Acceptance criteria:
    • All satisfied or
    • Documented reason for not being performed or
    • Split to separate ticket and ticket is linked by relevant AC(s)
  • Above PR sections adequately filled out
  • If any breaking changes, in accordance with the pre-1.0.0 versioning guidelines: a CU ticket has been created for the VA Mobile App detailing necessary adjustments with the package version that will be published by this ticket
• Code
  • Tests are included if appropriate (or split to separate ticket)
  • New functions have proper TSDoc annotations

Publish

If changes warrant a new version per the versioning guidelines and the PR is approved and ready to merge:

• Merge main into branch
• Merge branch to main
• Publish new version after merging

[TimRoe]

Approving code-wise, but:

PR is linked to ticket(s)

doesn't seem satisfied in that the in-write-up link says ticket 53 but goes nowhere and the PR itself is connected to a storybook-dark-mode ticket that, while related, is not in our repo/shouldn't use the built in connection as this PR isn't closing out the storybook-dark-mode issue.

Since it's a small change, would be fine with it moving not linked to a ticket if an appropriate one hasn't actually been created.

[narin]

Fixed link. Couldn't connect it to the issue since it was closed already. ZenHub automatically connected the referenced storybook issue. Removed the connection.