Summary

Fixed a JS error that was reported inside the console when trying to focus the select element.
Upsell the Database option only to New Personal, allow access to old Personal plans
Changed the upsell message from:
Upgrade to Developer plan to activate this feature!
to:
Upgrade to Plus plan to activate this feature!

For Free users, the message should be:
Upgrade to Pro to activate this feature!

Will affect the visual aspect of the product

YES

Screenshots

Test instructions

1. On a fresh instance install Visualizer
2. Check the Free Upsells messages
3. Activate an Old Personal plan
4. Check that the Database option is available.
5. Activate a New Personal plan
6. Check that the Database option is not available.
7. Check the Upsell message.

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 Codeinwp/visualizer-pro#468.