feat(theming): implement a ThemeController

[msyavuz]

SUMMARY

Implement a ThemeController that handles theme injection and persistence that can be overriden for different methods of storage. This pr also includes a ThemeSelect component that loads prefers-dark-scheme by default and persists dark/light/system.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

After:

TESTING INSTRUCTIONS

Select from Light/Dark/System and refresh the page. Theme mode should persist.

ADDITIONAL INFORMATION

• [ ] Has associated issue:
• [ ] Required feature flags:
• [ ] Changes UI
• [ ] Includes DB Migration (follow approval process in SIP-59)
  • [ ] Migration is atomic, supports rollback & is backwards-compatible
  • [ ] Confirm DB migration upgrade and downgrade tested
  • [ ] Runtime estimates and downtime expectations provided
• [x] Introduces new feature or API
• [ ] Removes existing feature or API

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@geido Ephemeral environment spinning up at http://44.247.55.168:8080. Credentials are 'admin'/'admin'. Please allow several minutes for bootstrapping and startup.

[github-actions[bot]]

@msyavuz Processing your ephemeral environment request here. Action: up. More information on how to use or configure ephemeral environments

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@msyavuz Ephemeral environment spinning up at http://35.86.77.167:8080. Credentials are 'admin'/'admin'. Please allow several minutes for bootstrapping and startup.

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@msyavuz Ephemeral environment spinning up at http://34.210.70.21:8080. Credentials are 'admin'/'admin'. Please allow several minutes for bootstrapping and startup.

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@EnxDev Processing your ephemeral environment request here. Action: up. More information on how to use or configure ephemeral environments

[github-actions[bot]]

@EnxDev Ephemeral environment spinning up at http://35.161.4.156:8080. Credentials are 'admin'/'admin'. Please allow several minutes for bootstrapping and startup.

[msyavuz]

@msyavuz I didn't see the icon to choose the mode

You need to have the feature flag for it to show up. Let me add it to testing instructions!