Add Sales channel page to promote Ecomdash plugin adoption

Proposed changes

To improve the visibility of the EcomDash plugin to our Ecommerce plus customers.
If a customer has the Ecomdash entitlement, then the customer should see the Ecomdash landing page from the Store navigation under "Sales Channels".
When a customer clicks on the page the first time, the CTA Get Started, it should open a new window with the Ecomdash onboarding.
After a customer has setup the Ecomdash plugin, the customer should see the landing page with Open Dashboard as the CTA instead of the Get Started CTA.
Related BlueHost PR
Figma

[ ] Bugfix (non-breaking change which fixes an issue)
[x] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[ ] Documentation Update (if none of the other choices apply)