Additional image url and logo customizations

[Charlesthebird]

This PR

• Updates the environment variables so that the image URL's can be customized.
• Updates the readme with how to use the new customization options, and adds some screenshots to it.
• Updates the pagination controls so that they are only visible if needed (it looked strange to have them with only one API Product here).
• Adds a VITE_COMPANY_NAME environment variable to customize the company name (this can be still done through tmplr variables like before, or manually, but the environment variable makes it consistent with the other customization options).

Resolves https://github.com/solo-io/gloo-mesh-enterprise/issues/17759