Replace all references to "normal" style with "light" style in codebase

[richorrichard]

Is your feature request related to a problem? Please describe
The documentation has been updated to reference Storybook's built-in "light" theme instead of a "normal" theme, but there is currently mixed use of "normal" and "light" themes in the codebase.

Describe the solution you'd like

1. Find all named references to the "normal" theme.
2. Replace all with references to the "light" theme.
3. Update tests and snapshots as needed.
4. Verify that end-user installs that override/modify the "normal" theme continue to work as expected.

Describe alternatives you've considered
n/a

Are you able to assist to bring the feature to reality?
Yes please! I'd love to take on this issue. I might need some help from a core team member to make sure that changes I make don't cause unforseen issues

Additional context
n/a

[stale]

Hi everyone! Seems like there hasn't been much going on in this issue lately. If there are still questions, comments, or bugs, please feel free to continue the discussion. Unfortunately, we don't have time to get to every issue. We are always open to contributions so please send us a pull request if you would like to help. Inactive issues will be closed after 30 days. Thanks!

[shilman]

Shiver me timbers!! I just released https://github.com/storybookjs/storybook/releases/tag/v7.0.0-alpha.10 containing PR #17034 that references this issue. Upgrade today to the @future NPM tag to try it out!

npx sb upgrade --prerelease

Closing this issue. Please re-open if you think there's still more to do.

[shilman]

Gadzooks!! I just released https://github.com/storybookjs/storybook/releases/tag/v6.5.10-alpha.0 containing PR #17034 that references this issue. Upgrade today to the @prerelease NPM tag to try it out!

npx sb upgrade --prerelease

[shilman]

Ta-da!! I just released https://github.com/storybookjs/storybook/releases/tag/v6.5.10 containing PR #17034 that references this issue. Upgrade today to the @latest NPM tag to try it out!

npx sb upgrade