Fix: [i18n] Added text domain to strings

[cristian-ungureanu]

Summary

Added text domain to strings in PaletteForm.js
Fix to admin.php file for displaying color palette and SS notice text translations

Will affect visual aspect of the product

YES/NO

Screenshots

Test instructions

1. Install Poedit and generate a language file, you can use this video: https://www.youtube.com/watch?v=HzcZeNZu7To&ab_channel=AuroobaMakes.
2. Translate "Try one of our ready to use Starter Sites" which is the button text of our welcome notice
3. In WordPress, switch to your new language in dashboard settings
4. Check the notice button text

Check before Pull Request is ready:

• I have written a test and included it in this PR
• I have run all tests and they pass
• The code passes when running the PHP CodeSniffer
• Code meets WordPress Coding Standards for PHP, HTML, CSS and JS
• Security and Sanitization requirements have been followed
• I have assigned a reviewer or two to review this PR (if you're not sure who to assign, we can do this step for you)

Closes #4096

[pirate-bot]

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[irinelenache]

@cristian-ungureanu Tested and everything's fine on my end 🚀

[pirate-bot]

🎉 This PR is included in version 3.7.0 🎉

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