Replicate Docker Hub frontend routing

[guacamole]

On DockerHub, some of the popular (and most used endpoints IMO) are:

• /r/<username>/<image> - Details of a container image
• /u/<username> - List all repositories of a user (List Public images for everybody and all for the user)
• /r/<username> redirect to /u/<username>

Our routing is a little different:

• /u/<username>/<image> - Details of a container image
• /repositories - List all repositories of a user
• /u/<username> - 404 Not Found

For example:

• https://app.openregistry.dev/u/jsdp/alpine
• https://app.openregistry.dev/u/jsdp - Throws 404