Add and make use of a constant in settings for the product name.
Review Request #1781 — Created Nov. 13, 2019 and updated
Throughout the product, we've always hard-coded the product name as "Review Board", which we then had to override in RBCommons, often resulting in a mix of names. Sometimes this is appropriate (as we're not hiding that the product is Review Board underneath), but often it is not and can end up being a bit confusing. This adds a new `settings.PRODUCT_NAME` constant that we can use throughout the product. It's defined as "Review Board" here, but we'll be able to override that with "RBCommons" and reduce the number of templates and other code paths we have to override, making future merges easier. Testing Done: Tested all affected pages with and without a custom product name. Unit tests pass. Reviewed at https://reviews.reviewboard.org/r/10751/