feat(themes): enable all palettes (#30874)

Issue number: internal

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## What is the current behavior?
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The new theming structure does not allow high contrast and high contrast
dark to render properly. This can be seen when running a test that uses
`set-content`.

## What is the new behavior?
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this PR. -->

- High contrast and high contrast dark have been enabled to the testing
environments
- The theme files for high contrast and high contrast dark have been
added under `themes`.

## Does this introduce a breaking change?

- [x] Yes
- [ ] No

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## Other information

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screenshots of how the component looks before and after the change. -->

[Colors
preview](https://ionic-framework-git-set-content-ionic1.vercel.app/src/themes/test/color/)

How to test:
1. Verify that tests related to palettes are passing especially those
that use `setContent`
2. Verify that the preview page renders the right colors for each
possible variation of palettes and themes

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Co-authored-by: ionitron <hi@ionicframework.com>
Co-authored-by: Brandy Smith <brandyscarney@users.noreply.github.com>