Add upgrade buttons

[thijsoo]

Context

• We want to add an upgrade button to the sidebar and the admin menu.

Summary

This PR can be summarized in the following changelog entry:

• Adds an upgrade button to the sidebar and admin menu.

Relevant technical choices:

• The sidebar button works with a link to a page and the page is just a redirect to the correct yoa.st link.

Test instructions

Test instructions for the acceptance test before the PR gets merged

This PR can be acceptance tested by following these steps:

• Make sure you only have free enabled and not WooCommerce(woo) and Yoast SEO premium(premium)
• Make sure the sidebar and top bar buttons looks like the ones in the design. For the top bar one make sure the url is:
  admin-bar-get-premium and for the sidebar one turn on preserve log in the dev tools from chrome and make sure the redirect url is: https://yoa.st/wordpress-menu-upgrade-premium
• Enable woo and make sure the links change to wordpress-menu-upgrade-woocommerce and wordpress-menu-upgrade-premium

Relevant test scenarios

• Changes should be tested with the browser console open
• Changes should be tested on different posts/pages/taxonomies/custom post types/custom taxonomies
• Changes should be tested on different editors (Default Block/Gutenberg/Classic/Elementor/other)
• Changes should be tested on different browsers
• Changes should be tested on multisite

Test instructions for QA when the code is in the RC

• QA should use the same steps as above.

QA can test this PR by following these steps:

Impact check

This PR affects the following parts of the plugin, which may require extra testing:

Other environments

• This PR also affects Shopify. I have added a changelog entry starting with [shopify-seo], added test instructions for Shopify and attached the Shopify label to this PR.

Documentation

• I have written documentation for this change. For example, comments in the Relevant technical choices, comments in the code, documentation on Confluence / shared Google Drive / Yoast developer portal, or other.

Quality assurance

• I have tested this code to the best of my abilities.
• During testing, I had activated all plugins that Yoast SEO provides integrations for.
• I have added unit tests to verify the code works as intended.
• If any part of the code is behind a feature flag, my test instructions also cover cases where the feature flag is switched off.
• I have written this PR in accordance with my team's definition of done.
• I have checked that the base branch is correctly set.

Innovation

• No innovation project is applicable for this PR.
• This PR falls under an innovation project. I have attached the innovation label.
• I have added my hours to the WBSO document.

Fixes #

[vraja-pro]

🚧 When clicking on the upgrade button when woocommerce is disabled and Yoast SEO premium disabled, I'm am redirected to a black admin page.
Also the Black Friday design is not the same, maybe thats for a different issue?

[vraja-pro]

CR & AC ✅