[Manage Public Key] Add new route, and empty page

[stephenkao]

Problem statement

The sender emails us two separate public keys. These keys are stored in the database under sender settings. Then we send them an email that they can start testing (authentication) and includes the API endpoint to point to and link them to API Programmer's guide.
This happens on almost every new sender and is a manual process.

What you need to know

https://www.figma.com/file/6mwI5ac6rprACKDzDo4Ady/ReportStream-Workspace-%7C-2023?node-id=1883-20071&t=DaL5Q5yF7wMvJyiV-0

Acceptance criteria

• Add a new /resources/manage-public-key route
• Page will only be accessible if authenticated as a Sender.
• Will be redirected if not logged in as a Sender.

To do

• create route
• create page