Update group/project access email to include reference to Organization

What does this MR do and why?

Update the project/group access granted email to include reference to the Organization.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Before	After

How to setup and validate locally

1. In rails console run Feature.enable(:ui_for_organizations)
2. Go to http://localhost:3000/rails/mailers/notify/member_access_granted_email.txt to see the email previews
   • Change the Format to toggle between the HTML and plain text view.

Related to #465861 (closed)