This formalizes the concept of a 'UI user' which is a local
user that can call APIs the same way that UI does it.
The server will now allow access to:
- UI user (identified using `--server-username` with password specified
using `--server-password' or `--random-password`)
- remote users with usersnames/passwords specified in `--htpasswd-file`
- remote users defined in the repository using `kopia users add`
when `--allow-repository-users` is passed.
The UI user only has access to methods specifically designated as such
(normally APIs used by the UI + few special ones such as 'shutdown').
Remote users (identified via `user@host`) don't get access to UI APIs.
There are some APIs that can be accessed by any authenticated
caller (UI or remote):
- /api/v1/flush
- /api/v1/repo/status
- /api/v1/repo/sync
- /api/v1/repo/parameters
To make this easier to understand in code, refactored server handlers
to require specifing what kind of authorization is required
at registration time.
689ed0a851