Update the routing and app title for the new standalone apps

[willmcvay]

Background context or User story:

Currently we prefix our routes with client, developer and marketplace in the marketplace app. This is not necessary now since the apps are all standalone

Specification or Acceptance Criteria:

• Route prefixes should be removed from the three standalone portals so where a route is /developer/apps now, it will just be /apps
• HTML title attributes should be updated to 'Marketplace', 'Developers' and 'Admin' respectively
• For Marketplace app only, if I try and land on either an /admin/* route or a /developer/* route, please show a dialogue page (use the developer edition download dialogue for the UI base). Dialogue should contain:

Heading: "Looking for the developer portal?"
Body: "The developer portal has permanently moved to https://developers.reapit.com Please remove any bookmarks to this page and in future visit the developer portal direct. Thankyou."
Footer: Button with text "Go there now", linking to the correct dev/prod instance and another "Back to Marketplace" linking back to the browse apps page.

For admin, replace developer specific text with admin

For now, we will still let a client account log in to dev/admin portal (and vice versa), then check the id token / login identity to check they have a clientId, developerId or adminId (as relevant). If they don't, show them the redirect message for client or developer portals and a 404 for admin portal

Suggested solution:

• Probably simplest to do this as 3 PRs so they don't get too large